I used it during probably 2-3 years of school with no negative effects. Use was conservative, probably 3-5 times per year (5 being the absolute max) evenly spaced with 2 month breaks at minimum and experienced no effect on grades or anything else. Would always drop at concerts with friends or my girlfriend. Dosage was generally in the 150-200mg range although have bumped up to typically doing 150mg followed by a 80-100mg redose. Single doses in lower amounts like 150mg definitely had less impact on how I felt the next day/week although even the slightly 'heavier' use wasn't bad.
IMO, use should be kept to a moderate amount with *priorities* in mind. Drugs should be used in such a way to enhance life, not cause negative effects. The minute drug use began negatively influencing my grades or work performance is the minute I would have cut them out without hesitation. People get so fucked up on priorities that they begin sacrificing the bigger picture for a few moments of temporary pleasure.