I'm leaning towards Ian's camp here, almost 23k and still minimal visible wear on mine. I use DuPont's dry Teflon lube when I remember but I definitely exceed any 500 or even 1000 mi. routine. Like Ian, I also think those sticky chain lubes turn your chain into a file wearing down the sprockets at an advanced rate.

A positive attitude may not solve all your problems, but it will annoy enough people to make it worth the effort. Herm Albright (1876 - 1944)