I run 500hr oil change intervals on my old mechanical motors. I have Deere 6059s running original everything's with over 22k hours.
I did lose the third 6059 at 19k hours when the balancer separated. Windowed the block and oil pan with a main cap. Drove it on a trailer with no oil, drove it off at the other end, with no oil...innards looked like a 5k hour motor, save for the added ventilation.
I just don't see a problem with 500 hr intervals.
I'm running 400 hr intervals on all my newer stuff, though.
Never seen a sample that says that I'm doing it wrong on either interval.