I, with a peculiarly high tolerance for substances, have studied for finals high. I always found finals to be the easiest tests of the semester, I guess because I have this weird tendency to actually absorb the content throughout the semester and add it to my reservoir of knowledge.:tin foil hat:

i find it's really hard to go cold turkey if you're used to being stoned most of the day. So since I smoke small amounts at relatively distant intervals, it's not hard to go a while without smoking. Generally, you can change and train your body to conform to any smoking schedule, it just takes a week or so to break yourself in.