Reddit's college football page is doing a cool exercise in which they examine how often teams play the other power five conferences. And as it turns out, Northwestern is better than everyone else in the Big Ten at playing teams from all across the nation.
Note: Please don't confuse this with having a great strength of schedule. NU has generally played pretty mediocre (or worse) power conference teams.
The Wildcats have at total gap of 13 years since they've played all the conferences. Compare that to Purdue, which has a 144-year gap, thanks to not having played a regular season game against the SEC since 1942 and the Big 12 since 1958. The conference, as a whole, is great about playing the Pac-12 and bad about playing the SEC, though some of that is likely due to the fact that the Big Ten and SEC meet so often in bowl games.
Plus, everyone in the SEC besides LSU, Alabama and Missouri is pretty LOL-worthy when it comes to playing all of the conferences. Somehow, Arkansas has never played an ACC team and Ole Miss has never played a Pac-12 team during the regular season.
Expect NU to have fewer meetings with power conference foes in the coming years, once the Big Ten switches to a nine-game schedule. In fact at this time, according to FBSchedules.com, the Wildcats only have ACC and Pac-12 teams on the schedule through 2022. The Big 12 drought, in particular, looks likely to continue. Those schools also play nine conference games and the only "like-minded" school that could maybe fit for a home-and-home would be Baylor.