You mean Top 50?
I think it’s a stretch to say that schools outside of those 1100 are sending ⅓ of their kids to the Top 50, unless you’re including tiny magnet and charter schools where ⅓ is not big.
I still think mailings could get much more selective. My school (in the NE, so that might change the prestigious school familiarity thing a bit) we do need frequently send a single student to Harvard, although it did happen just a couple years ago. But that’s because most years, we don’t produce a single student who is qualified for Harvard.
I do think there are less well-known schools - especially schools that are just slightly less prestigious, meet need, and are in different regions of the country - which are great options that students might not know about. But the Stanford mailings? Not necessary.
Also worth mentioning - Harvard seems to only send mailing to students with NMF-level PSATs or something like that in this region, though Stanford and Chicago and all the others don’t have the same high threshold.