Alabama, Clemson & Georgia are always in the Top 15. LSU, Auburn, Florida, North Carolina & Miami are frequent visitors; and here lately, so is UCF & Memphis. Ohio St., Notre Dame & Penn St. have the most staying power from the Northeast quadrant, but Cincinnati, Michigan, Iowa, Iowa St. & Wisconsin are frequent visitors. Occasionally you can find Minnesota, Northwestern & Iowa.10? You exaggerating a little, just maybe? lol Clemson & Bama(sure), LSU(sometimes), Florida(sometimes), Miami(not so much anymore), FSU(not so much anymore), Ole Miss(only occasionally). So Carolina(almost never), Arkansas(almost never), Tennessee(almost never), Kentucky(almost never), UNC(almost never), GTech(almost never), Virginia(almost never), Auburn(sometimes), Miss St(only occasionally).
So it's more like 4 or 5. imo
The Southwest quadrant is most often represented by Oklahoma, but may also include Texas A&M, Texas, Oklahoma St., USC & Utah. The Northwest has less solid representation, but usually includes Oregon & Boise St., and sometimes Washington & Stanford.
Every year is different, but some schools show up more often than others.