It is irresponsible to recommend less than three hours to an unknown tourist arriving at the airport at any time.

And if you arrive 2 hrs in advance, what are you going to do with that extra hour ? Visit a museum? Can anyone guarantee that there won't be a traffic accident on the road that you take to the airport ? Better to arrive an hour early and relax in the departure lounge rather than getting hysterical if you arrive late and the lines are long.