I've never had to walk my bike more than 2 miles on a 10 mile commute so I'd say that's pretty good.

That being said my wife and I were riding the tandem to a charity run downtown one day. Got a flat on the way. Changed it. Got another flat. We were on an industrial stretch and had to *run* the bike to a major avenue crossing about 3/4 miles away (we were on an industrial corridor). Locked it up. Taxi to the run. Ran the run. Buy t00bs. Taxi to the bike. Fix and ride bike...... another flat!!! Walk it to friends house that we were headed to. Get drunk. Leave it there. Pick it up with car the next day. Ugh.

We put about 8 miles on the tandem that day and 12 miles on our feet.