I travel multiple times a month and have NEVER missed a flight when arriving to the airport 60-minutes prior to my (domestic) flight. In fact, I can only recall ONE time that I cut it close (due to heightened security and super long lines).

If you have pre-check or CLEAR, there's zero need to arrive 2 hours before your scheduled (domestic) flight. You can if you want, but it's not necessary. When I travel with family, I go earlier, just to make the whole process slower and less rushed.