never have a limit, though i have been too high, on several occasions, i just got to the point where i actually was just so out of it that it gave me a headache, and i know that if i continue smoking that i would smoke myself sober, which overall would be a huge waste. I mean going through a quarter of some powdery seedless, stemless shake in one evening made me pretty much just pass out once not right after i took a hit or anything, but about 20 minutes later i was laying on a bed, then i woke up about an hour later to see some friends at the party too, so i smoked another one with them, and thats when i knew it was where i was ready to stop for the evening.