"Let's see how many unbeaten years USC has when they play Tennessee, Georgia, LSU, Auburn, Alabama and Florida all in the same year." And how many of those teams did Texas play?
The point is that Auburn and LSU had to play all of those teams in their championship years. Ohio State also had to beat all of the quality Big-10 teams in their championship years too. LSU also beat Oklahoma and Auburn beat Virginia Tech in their championship years.
Basically the regular season is a warmup to the USC - the same way it used to be to Nebraska in the early 90s. That is a huge advantage as you don't have many injuies and since there are so few high quality teams, the odds of going unbeaten and playing for a championship are almost guaranteed.