Reducing tolerance whilst increasing the depth of your highs is easier than you might think.
It sounds counter-intuitive, but for tokers with a high cannabis tolerance, it's a bad idea to have too big a bowl on the first hit of the day, or two or three bowls in quick succession, to try and get a strong high that overrides your tolerance. It may well give you a good high (which will tend towards being a bit too 'bright') – but this big first hit is creating instant tolerance to the following hits you're going to take after it. Later bowls can't have the same impact as the first ones did, because the first bowls filled up the THC receptors in your brain. If you do take more, even a lot more, you'll either end up falling asleep, or the highs will clash and cancel each other out. No matter how high your tolerance is and how much weed you think you need to get a good high, try just one single bowl on your first hit of the day, just as an experiment. You'll be surprised how high it can get you and how long it will last if you let it run its full course.
To try and explain this effect, imagine that your THC receptors are a series of ten cups. Now, you might think that if you can fill up all ten when you smoke that you're going to be incredibly and wonderfully high, but thats not actually the case. The best and deepest highs actually happen when number eight is reached, and after filling up cups nine and ten, the high becomes more of a rush that can have some unpleasant side effects, take you out of a high state as you might normally recognise it, or simply not feel that good.What you'll recognise as a good high will actually take place once the contents of nine and ten have been depleted and the high reduced.
So, if you're a daily user like myself, one way (there are a few) to reduce tolerance is to continually have say, a third of your normal bowl size, which will take you up to receptor number eight, but not over it. You might think if you are a regular user that such small amounts would not give a decent high and would be a waste of time, but I've actually had much longer and better highs by reducing the amount I smoke. For the first couple of days of using this method you'll find that the high takes slightly longer to come on (for me about ten or even twenty minutes) as it would if I were eating it, but the high is certainly much better for it. I also found that I needed to top up less often, so not only did I start getting better highs, but my consumption went down by about half - for the same effect as having much, much more.
Give it a try, it's helped me continue to be a daily user for over 25 years with hardly a day off except through illness or dire circumstances.
(Extrapolated article from 'Cannabis & Meditation - An Explorer's Guide' (Second Edition)