I just replace the tube because my patch jobs never seem to hold up, but normally I don't do flats.

Well, not usually. I was riding to work about 6 months ago, and just happened to think to myself, "Myself, it's been maybe 6 years since you've had a flat tire! I guess the thorn-resistent tubes and tire liners are doing their jobs! Probably the only way you'd get a flat, Myself, is if, through some freak of nature, you got punctured through the sidewall."

Jinx. Less than ONE MILE LATER I ran over a broken off jack-knife blade with my front tire, which caused it to jump up and dance around, until my rear tire got to it, at which time it launched itself (you guessed it) right through the sidewall.

Since then I've decided to think only happy thoughts when I'm riding.