I just want to reiterate that THC is not a hallucinogenic, and there is no absolute formula. What is interesting about cannabis is that very small doses can work. We know that the average amount, in data from Israel, the Netherlands, and Canada, is about one milligram, 1.5 milligrams, or 0.67 milligrams in the Dutch study. That's the average amount of dried cannabis per person per day, and yet veterans will often use three milligrams. There are people who use five or 10 milligrams of cannabis.
The individual variance is a very difficult thing, and nobody has ever been able to explain why this is the case. Tolerance is a bit of it. You know the word “tolerance” and what it means: If you get used to something or your system gets used to it, you sometimes need to have more of it.