For comparison Clemson and BAMA have made 6, OSU and OK 4, ND 2, in fact,
Some combination of those top 4 teams (Clemson, Alabama, OSU, Oklahoma) have occupied 3 of the top 4 spot every year except the first, that year two Cinderella’s made it in (Oregon and FSU). So basically 3 spots are taken before a down of football is played, there’s only one spot up for grabs each year for the rest of the P5, and no chance for G5.