Below (right) is a worn, but very usable rear Ironman sprocket. This sprocket is just at the .025" wear limit. This sprocket has been run for over 1000 hours on a 2002 and 2003 KTM 525. It required two bikes, five O-ring chains, and 31 Dunlop 695 rear tires to wear it out by an expert 220-pound desert/enduro racer who practices and/or races 10 hours per week.
This is typical wear in western desert and mountain conditions. Mud accelerates wear, but our sprockets will still outlast an aluminum Renthal in mud conditions, by 10 to 30 times. From experience, the 1000 hours in the below instance would have easily consumed 30 expensive aluminum sprockets. As most serious riders know, a powerful 450 eats sprockets at about the same rate as rear tires. 30 sprockets at 60 each is a whopping 1800.The sprocket below on the left is a Sprocket Specialists aluminum with hard anodizing. It has 16 hours of sand racing/practice on it.