Does getting to peak mileage early on blunt potential fitness gains?

Ignoring the potential risks, does getting to lifetime peak training load quickly yield less fitness gains than getting to it more slowly. If someone built from 40 mpw to 100 over the course of a year, held that mileage for years, would they end up with the same fitness as what they would've had if I had spent 5 years going from 40 to 100?

Are there any twin case studies of this? Where two twins did the same training in high school, ran the same times, and went to different colleges where one built them up slower and one built them up less slowly.

I've tried looking at elite runners' training but I can't tell what to make of it. Most yearly increases aren't more than 1.25 hours a week a year, and when they are it's usually the transition from high school to college, which involves a decent amount of athletes not improving, so that makes me suspect that more than 1.25 hours a week a year is potentially problematic, but athletes not doing well at first could be due to so many other factors. Ethan Shuley increased by 4 hours a week in the last year, and he is running pretty well. I also can't really tell if this pattern exists because this is just how things are done.