You know, I have faithfully gotten to the airport at the requested times, 2 hrs domestic and 3 for international. Often when I get there the security lines are from hell. As a smoker, I can't imagine waiting in line to clear security for an hour then waiting at the gate for another hour or so with no chance of a cigarette till I've reached my destination, so I spend the time outside till about 30 minutes before my scheduled departure.

Without fail, when I go back in, there has been no security line to speak of, maybe 5-10 minutes. I don't know if I'm just lucky, or if the timing just works so that at the end of the 'bank' of flights, everyone else has cleared already.