Yeah, I usually get about 5000-6000 miles before a chain's worn to 1/8" stretch. I usually replace it before then, somewhere between 1/16 to 1/8", so around 4000-5000 miles.

Riding in the rain's the worst thing I've done to my chain. Maybe it's the water washing away the lubricant that causes it. So the chain's lubricated only with water on the ride. Even with cleaning & soaking the chain immediately after the ride doesn't help, the wear's already occurred.