Yeah, I don't return them unless they're bad either, but one nice thing about WM batteries .... WM's are EVERYWHERE! So if one dies at an inopportune time, Wally World is usually not too far away!
My Old Man has used this approach for his trolling motor batteries for years. They usually out live the warranty, but if they don't and you happen to be on a fishing trip when they fail, you can usually find one nearby and not lose the whole day of fishing trying to chase the warranty at a particular store.