Not that I’m asking you to do research on this, but it makes me wonder how many times the “great” SEC has had teams with perfect records in conference play. Maybe the Big Ten had tougher in-conference competition over the years.
But there might be another factor here for the Big Ten that I don’t think impacted the SEC. And that is: for so many years the traditional arrangement was for the Big Ten going to the Rose Bowl where, in a number of matchups, they played USC or UCLA. I would contend that was a home-field advantage of sorts in that USC and UCLA got to work out in their regular practice facilities, stay in their own beds, etc for a longer period of time than the Big Ten teams. And, of course, they had more fans who lived nearby. I know USC had some ridiculous W-L record in the Rose Bowl. So maybe this too helped account for fewer perfect seasons by Big Ten teams.