Comment by johngossman

I've always assumed they tell you to arrive early in order to account for the chance it will take you longer than you guess to get there, just like doctors do. I've never had it take 2 hours from arrival to gate, but I have been 90 minutes late because of traffic and would have missed my flight (not a big deal) if I hadn't aimed for being there two hours early. In any case, the assumption that this time is wasted is spurious whether you're a road warrior catching up with e-mail or a tourist researching your trip, you're not sitting in a lounge chair like a zombie.