The Duke question is an interesting one. Does NU get much, if any, benefit from playing them from a recruiting standpoint?
As far as I can tell, only 2 players who NU offered in the 2021 class chose Duke: CB Brandon Johnson, from North Carolina, and S Placide Djungu-Sungu. They both had decent offer lists but weren't standouts.
Here's what that looked like from 2016 through 2019 (# of players with an NU offer who chose Duke):
2019: 4
2018: 2
2017: 5
2016: 3
That's not nothing... but it's also not a lot. And it's not as if these are the absolutely top, A list guys in each case.
I think it's pretty clear when looking back on recruiting classes, and, most recently, Austin Uke's hat dance, that Stanford remains stiff competition for academically minded high 3-star low 4-star recruits. And the other main non-conference rival for the best Midwestern recruits is obviously Notre Dame.