Since the subject matter here is "thin 9mm" and that applies directly to the smallest/shortest pistols - I think that 500 rounds of "proving" may be excessive for some models.. not because they wont take it, but because some of them should have a new recoil spring or the extractor may be wearing by then.
Proving it out too far may be counterproductive if a part needs/should be replaced. You'd have to start all over, then repeat.
A few brands require 200 rounds of "break in" and I'm fine with that, once accomplished with no issues from 50 thru 200 I call it good, with 200-1000+/- being the sweet spot of expected reliablity. YMMV.