Just look at what Jane did on her All Access video 3x3200, 2x800 and 150m fast. Yes the times were insane, but her effort was completely chill. She would be totally fine to do it again 48 hours later if needed. Can you imagine even in 2010 doing 7+ miles of work as a HS girl? She probably ran 11 miles that day.
15 years ago We had a distance coach that thought 6 miles was a LONG RUN. We did 300 repeats hard almost weekly, had workouts where he would literally pull reps out of a hat, and he insisted we should only run 2 miles the day before every meet. It's honestly unbelievable what we still accomplished training like we did from February through May.
There were (and still are) teams training WORSE than that. We had a 1:55 guy, a 4:20 guy and and 9:30 guy - just imagine that those guys exist all over the place and what they could do with better coaching.
Literally 1 year of college training and I went from a 9:45 2 miler to an 8:30 3k. The training wasn't even perfect, it was WAY too hard for us walk-ons (we ALL ran tempos at 5:00 pace as a team), but just the amount of work we did was drastically different to the point I smashed my 5k PR in an 8 mile LT.
Now imagine HS seniors are training like college freshmen - but rather than being thrown at the wall and seeing who breaks, the training is challenging, but actually tailored to the kid. Add that to Strava, shoes, better competition raising the bar for everyone - I'm honestly surprised that we aren't seeing even MORE depth than we already do.