Sure some pistons break. But most of them are OK at the overhaul, most of them can be used for the next overhaul, and the next. I have seen pistons go through about 3 overhauls, with maybe a spacer to close up a widened groove. That is thousands of hours at say an average speed of 2500 revs or about 1/5 the reves our models go. So I would surely expect our model ringed engine pistons to last maybe 1000 hours.