Interesting post, worth a read. It seemed pretty US-centric, and I'd be curious to see how data compares in other countries where school is done differently.
I'm reminded a little of Ivan Illich's take on education being a net negative. https://en.wikipedia.org/wiki/Deschooling_Society
Not sure I agree, but some decent points are in there.
What countries do you have in mind? Where is school done differently? Early start times at least seem to be a problem everywhere.