Ultimately, YC exists for the benefit of the investors. It's symbiotic with startups, of course, but the measure of success is ultimately the return YC achieves

Ultimately, YC exists for the benefit of the investors. It's symbiotic with startups, of course, but the measure of success is ultimately the return YC achieves for itself. It seems unlikely that anyone but the inner circle has that data, but given the type of people that run YC, I'd expect they experiment and then observe results, refactor, experiment again, ultimately heading in the direction of what improves their return. I'd be surprised if they haven't debated class and check sizes at great length since the beginning, and then settled those debates by observing the results of the changes over time.