For me it usually lasts around 3-4 hours. I never go above the second plateau, though; three and above could last longer, I don't know.
if i remember correctly, the most intense part of the trip will last somthing like an Hour, but, you wont want to be near a parent for like 12 hours (for 3rd platue i recon - 600mg roughly). or 6 hours 300mg... ofcourse this all depends on how used you are to being around your parents in "altered perceptions"
i just lock my room door and trip out till it wears off and im like" wtf am i doin in my room still?":" but yeah.. 12 hours for 600_mg..or around 12 hours.. i never counted thou too
