This is what it really boils down to is ones disposition. Some like to cover all eventualities, others like to take risk. If a flat tire has not happened all year, why would it happen day I am on way to airport? If it does then so be it. We surely cannot guard against all eventualities.

I had a friend of mine like this who would head off to Gatwick airport 6 hours before the flight, incase the motorway was closed or something similar and I used to ask him why he didnt leave the day before and sleep there. At some point one has to draw a line. Indeed in many of my close shaves at the airport I get angry and come close to missing my check-in because some over-zealous travellers whose flights dont leave for another 3 or 4 hours are already in the same line trying to check in and I wonder whether they dont have other things to do than be in an airport 4 hours before a flight!

I have though come very very close to missing many many flights and can be stressful watching the traffic and looking at one's watch so really it boils down to how one is willing to put himself through stress and how one is able to cope with it.

I usually end up hanging around airports anyway because even when I cut it close the flights are often delayed.