In a broad sense, I have never been the "cut-it-as-close-as-possible" camp. I get wanting to minimize time in the airport. I am not going to show up 8 hours early for a flight. That said, I am not going to try to arrive 5 minutes before boarding either just to avoid sitting around either. I work with people like that, and most of them frequently miss flights or get on late, losing bin space and facing seat poachers. Time is one of those things it is better to have and not need than to need and not have.

There are ALWAYS unpredictable factors...traffic delays on the way to the airport being the topmost, but other things too..a little old lady infront you in the security line who is clueless etc etc. I make sure I am there at least 2 hours before. If nothing happens, I have no problem sitting in the airport. And if there is a delay, I still operate as if the flight is on time, because things can "undelay".