I ride a fixed gear and am pretty concerned about how quickly my chain seems to develop slack. Every so often, I must slide the axle farther back in the dropout to take up extra slack. It's not the axle slipping, I made sure to check that. This most recent chain seems like it's already near the end of its life and there's no way that there's more than 1500 miles on it. Is this normal? Just FYI, it's a lower end KMC Z chain and I skid, skip, and ride through all sorts of gross road conditions. I feel like in the past, I have had better experiences with something like a SRAM PC-1. Are Z chains known for a short lifespan?