We fly out of a very small airport - HHH. We always aim to arrive 2 hours before take off. 95% of the time, we make it thru security and are at our gate with at least an hour to spare. We use that time to hit the bathroom, grab some snacks, and watch planes take off.
however, this past trip, we arrived 2 hours early to our tiny little airport...and security took over an hour!!!! It was nuts! We didn't get in line for security (because DH has a small bladder, had to check luggage, etc) until about 620. At 720 we got thru. I knew our plane would start boarding at 730 and I was near tears. I hate rushing. We got to our gate, I put my stuff down, ran back and got the kids some breakfast sandwiches, came back, took them to the bathroom, DH ran to get his breakfast sandwich, and before he got back, we were in line to board. Had we arrived even 15 minutes later...we probably would have missed our flight. They loaded and were pushed back before the 8:00 scheduled departure.
There were a LOT of cranky/frantic people that morning who, assuming since it was such a small airport, they could arrive 1 hour before their flight and be fine. When we hopped in line at 620, the woman in front of us - her boarding was being called. She still had an hour wait for security in front of her.
Never can be too early, IMO