What tolerance is
Regular THC use downregulates CB1 receptors. The same dose reaches fewer receptors and produces less effect. This happens relatively quickly with daily use.
The ceiling nobody mentions
MacCallum and Russo note that daily THC doses above roughly 20 to 30 mg may increase adverse events or induce tolerance without improving efficacy, and suggest limiting total daily THC to 30 mg or less.
If you have escalated past that and are getting less benefit than you used to, escalating further is unlikely to reverse it.
Resetting
A period of abstinence allows CB1 receptor density to recover. Expect disrupted sleep and vivid dreams in the first week or two — THC suppresses REM sleep, and stopping produces a rebound.
Coming back at a genuinely low dose afterwards is the point of the exercise. Returning to your old dose immediately undoes it.
When it is more than tolerance
If you cannot sleep without it, if use has escalated steadily, or if stopping produces irritability and craving that interferes with your life, that is worth discussing with a clinician rather than managing alone.