I heard that your body builds a tolorance, say since I shroomed last friday will I still be able to fry pretty good this wednesday!!!!! since i am giving a half a week break.
You build a tolerance instantly which takes somewhere around 2 weeks to virtually completely clear, For best results you should wait a month in between trips or increase dosage for same effect.
jon_funk is on the money, the 'tolerance' effect is instant (it's based on chemical, not psychological factors, and thus it's irrelevant how often you've had them before etc). Wait at least a month, you'll get a lot more out of your shrooms that way...