I was thinking more about it, and I realized I've never gone a full year on derailleur cables. 2 years in a row, I made it one race season. Of course, I got a new bike this year that I did most of my racing on, so the other bike that got used the most from Oct-early March is still on it's fall '08 cables.

Farther back, I think I've always needed to replace derailleur cables 2x a year at least. The first time, the housing split. After that, I started having shifting problems, always in the rear. With non-Dura Ace cables, I would always replace the front at the same time. I'm going to experiment to see if the Dura Ace front cable will last maybe the length of 2 rear cables.

It's weird, but I think I change my cables more often than my chain!