I'm curious about one thing. I've heard a lot of people claim that it doesn't matter how long you hold a hit in, but I've never seen any scientific explanation/evidence that it doesn't matter. Logically, it seems to me that when you inhale, the smoke contains a certain percentage of THC, which will get chemically absorbed into the lungs like any other saturation type reaction. Most chemical reactions take at least a non-neglible amount of time, so to absorb THC should take at least a -few- seconds. I'm speaking in an entirely general sense, learned from a year of college chemistry, however I don't know much about the specifics of THC absorbtion.