I'd like to explain the responsible way to build a medicinal schedule around cannabis.

Before I do, I have to emphasize that this is not an approach for maximizing your high. This is the approach for people who are treating chronic conditions with cannabis that they can't talk to their doctor about for whatever reason. It will take a lot of the fun out of the process, and it requires a discipline that most recreational users aren't interested in. Finally, I am not a doctor, and I do not have expert level knowledge. This technique is the result of digesting similar information online when I became a patient, tested and refined by personal experience. As always, your mileage may vary.

The first step is to be clear with yourself about the benefits.

If you skip this step, you are flying blind. "When I take RSO and it works, I know it because my joints hurt less and my appetite comes back". You need an understanding of what relief is, or it becomes easy to fall into a routine where you go through the motions without getting any actual benefit. The first rule of responsible drug scheduling is "Don't do it just to do it." It's one thing to maintain a regular schedule of intake, it's another to intake repeatedly without any benefit just to keep up your schedule. "It's been about 8 hours, probably time for my next dose" is an OK thought. "I've been doing it every 8 hours but it's not helping any" is a warning to change your schedule, and probably an indication of built-up tolerance.

The second step is to be clear with yourself about the cost, and I don't just mean financially.

Obviously, you cannot maintain a schedule if you can't afford it. But there are other costs that you can't overlook. Cannabis is friendly, it doesn't come with a lot of extra costs, but don't let that fool you into thinking it's cost-free. Every dose raises your tolerance, that's a cost. Every high comes with a corresponding low, that's a cost. If your drug comes with any degree of stomach discomfort, that's another cost (and one you really, really don't want to downplay). If getting stoned gives you the munchies and you binge junk food, that's a cost too. I'm not saying "focus on the negatives", I'm saying "don't ignore them". Once you understand the benefits and the costs, you have the start of a framework for building a schedule. This is the hard part, and there is no quick way to skip it other than starting with a lucky guess.

The nature of your schedule should be "The minimum necessary to continue reaping the benefits".

This is where most recreational users duck out and thank me for my time. Our culture glamorizes over-indulgence, but if you're a serious medical user you don't get to play that game. Bigger doses mean bigger tolerance, and tolerance wins that arms race every single time. Think of it like driving a car with almost no gas left and a bunch of hills between you and the gas station. You need to use just enough gas to get up one side of each hill, and then coast, and then try to carry that momentum forward into the next hill. If you slam down on the gas to speed down the hills to get to the gas station sooner, you'll be out of gas before you get there.

Finding that "just enough" amount isn't easy, and it takes a lot of trial and error.

What makes it tricky is that if you take too much and build up too much tolerance, you have to give up the drug for a while before you can properly try again. It doesn't help you to calibrate your levels from a heightened tolerance. As long as you aren't binge-dosing, it only takes a couple of days for cannabis tolerance to soften, but that's still a couple of days going without relief, or finding it through a substitute. (Hot showers and long naps are a good start! More drugs is probably not a good start.)

Alright, if you've made it through all the precursors and you're still on board, here's the process.

If you skipped down to this part, please take a moment to read the whole comment, because this process is only for a specific type of user, and it won't help much as generalized advice. If you're a recreational user looking to control your habit, I have a better guide for you already written out. This process is also written with cannabis in mind. Tolerance rates for other drugs are different and will require different timings, but I'm not going into that end of things, because the further from simple cannabis you get, the harder it is to control for unintended contaminants (aka, other drugs in the mix). This process should work about the same whether you smoke or vaporize or ingest your doses.

1. Go without for 2 days.
2. This sucks, but it's too important to skip over. Remember, you're trading a few shitty days for a schedule that helps you avoid them in the future. You will return to this step every time you find your tolerance is too high. It sucks, but it's a cost for doing it right. On the plus side, the more often your practice the discipline of a tolerance break, the easier it becomes to do them, and the better you get and building self-control.
3. Take a small dose.
4. This should be the amount you'd give a total newbie who asked you to be gentle. It might not be enough on this day, it's better to do too little than too much. If it's too little, you'll get to do more soon. If it's too much, you're back to another 2-day break.
5. Every hour or so after your dose, actively run through your lists of benefits.
6. "I think taking this helps my joint pain. Am I feeling joint pain relief right now?" Don't feel like you have to lie to yourself, and don't answer the questions dishonestly. If you have the thought "I'm not getting that kind of relief, but I'm still getting this other kind of relief," that's OK! Add the other kind of relief to your list of benefits if it's not already there, and keep checking every hour. Yes, it's obnoxious, but if you need to it's worth setting an hourly alarm on your phone. You very much want this data to plan with, so don't be lazy about it!
7. Pay attention to the order that your benefits go away.
8. You might find a trend, say your joint pain always comes back before your gut troubles, that's valuable to know! You're going to want to know which benefits go away the quickest, and which ones last the longest. You're going to build your schedule around the benefits that last the longest, and use the other benefits as training signals. You do not want to pin your schedule to the benefits that disappear quickest, even if they are the benefits you care about most. This sucks too because it would be a lot nicer to re-dose as soon as the first benefits start to fade. But if you do that, you'll still build a tolerance that interferes with the rest of the benefits, and you might end up with too much tolerance for even the primary benefits.
9. When the full list of benefits has faded, wait two more hours.
10. This sucks, it means intentionally denying yourself relief for a little bit, but keep reminding yourself that these few hours are a small trade for an effective schedule. You won't keep these hours in your schedule forever, they are part of the initial calibrations. These are the hardest hours in the whole process, but you can put yourself through two hours, I believe in you!
11. For your second calibration, take the same size dose. Not more, not less.
12. You are now testing your tolerance. Do Steps 3 and 4 again, pay attention to your benefits, and take note of any benefits that you don't get or that don't last as long. Those are signs of tolerance, and ultimately your schedule is about mitigating tolerance.
13. If your benefits are lessened, you have a tolerance.
14. It's almost impossible not to have some tolerance, especially if you haven't gone back to sleep, so don't panic if you do. But track exactly how much of a difference there is, and put it in terms like "My second dose gave me joint pain relief for two hours less than the first dose." If you lose more than an hour of relief from a primary benefit, it means you're using too much or too often. It's up to you to decide between the two, but if you're not sure, try lowering the dose before adding more time between doses. Your goal is to be able to have nearly continual relief, so a smaller dose is easier to manage than more time between doses.
15. However, if you don't get one of your primary benefits during your second dose, this is a bigger warning sign.
16. It means you blew your tolerance up too much, and you're headed all the way back to step 1, including another shitty 2-day break. Use smaller doses in steps 2 and 6. Yep, this sucks, but trust me, it's worth it in the end. If you keep blowing your tolerance, you'll need to keep raising your dose, and you'll get less and less benefit out of each dose until it stops working at all. Then you have to do a hard detox without any cannabis for several weeks, including the crazy-ass dreams, the lack of appetite, and the general feeling of "fuck why did I let it get this bad". That's hell, so don't trick yourself into going there. You might have noticed that so far, the guidelines are "start small, and cut back from that", so you might be wondering "when is it appropriate to raise the dose?"
17. You only raise the size of the dose if the last dose didn't provide any benefit, and you only do so after sleeping.
18. The wording here is precise, the difference between steps 8 and 9 is whether you get any benefit. If you got no benefit at all, the dose is too small and you can increase it. If you get some benefits, but not a primary benefit, it means you're dealing with tolerance instead. I'm emboldening it again because this is the thing people mess up the most: Do not take bigger doses throughout a day. The size of your first dose in a given day is the size all of the rest of your doses that day will be. DO NOT INCREASE YOUR DOSE BEFORE SLEEPING FIRST.
19. If you can manage to sleep without a nightcap, do so.
20. It's much, much better for your tolerance if you don't dose right before bed. I recognize that for some people, a dose or relief is a prerequisite for sleep, but try your hardest to not consider yourself one of those people. If you need a rule, it's "You have to spend an hour in bed trying to sleep before you can consider a nightcap." You must give yourself a chance to sleep without a dose, because sleeping is when your body does the most work to lessen your tolerance, and it doesn't do a good job if you spend the night sleeping off a fresh dose.
21. Keep cycling through steps 2 through 6, including waiting two extra hours between doses.
22. When you get 4 days under your belt where you didn't blow up your tolerance, you've found the right size dose, and it's time to fine-tune the timing.
23. Lock in your dose size before continuing.
24. This is your dose for now, and it's the dose you'll keep using, maybe indefinitely. You will not go over this dose size, because if you do it will ruin your schedule. Accept it for what it is, understand that you put real effort into determining it, and trust yourself to stick to it.
25. Now we finally get to start trimming the extra hours out!
26. If you've happened across a good schedule already, you may not need to make further adjustments. Sometimes just keeping a regulated intake is enough to smooth over those two "extra" hours, which just means you got a bit lucky in picking out your schedule. But if you're still roughing out those two hours between every dose, this is finally the point that you can cut them out slowly. Start by knocking off half an hour. If you've been going for 10 hours between doses, try 9.5. Don't increase the actual number of doses in your day, just trim the spacing in between them. The time you cut here gets added to your sleep break, to keep you in balance. Stick to the new schedule for another 4 days, then if you still need to, trim another half hour off. Go slow with this, and don't use it as an excuse to let your tolerance get out of control.
27. Listen to your body, and keep in mind the order of benefits you deduced earlier.
28. The first benefits to fade are your warning signs. They don't mean "I better take a dose right now", but they do mean "the time for another dose is coming". With practice and patience, you will get a very good sense of which feelings in your body represent a readiness for your next dose. It takes a couple of months of this routine before you can do it by feel, so don't do away with your phone alarms or whatever you use to keep on schedule.
29. Your schedule is correct when it reliably provides your primary benefits without over-inflating your tolerance.
30. If you still feel the benefits but it's time for a new dose, wait a bit. If you can, mentally award yourself bonus points. Every extra hour you squeeze out of a dose is an hour less tolerance you have. It's OK to skip or delay doses, it's not OK to double up on doses even for "emergencies". The response to an emergency is something new, not more of the same.
31. If your schedule slowly stops working, you need to occasionally pepper in a day or two of tolerance break to keep things moderated.
32. Even a very well-tuned schedule usually requires a break every few months, if not more often. Yep, it sucks, but it's still better than not getting any relief due to a high tolerance.

Well, this certainly turned into a long post. If you stuck through all the way, I'm convinced you care enough to make this advice work. It really is a chore, and it's not a lot of fun, but this is the responsible way to figure out a regular schedule and avoids the most common causes of failure. However you approach the task, I wish you a lot of luck. Cannabis is a truly wonderful medication when you use it wisely, and can give you parts of your life back if you take the time to work with it. Good luck!