Other than $$$, is there another reason Ohio State is able to get 7 home games every year?
The teams with the highest revenue from home games can afford to buy a game or two a year, so they will have 7, perhaps occasionally 8 home games. Teams with less revenue from home games are willing to accept the paydays, so they will naturally have 5 homes games. To get around that, they often will buy a game of their own, from an FCS team, to get back to six home games. Teams can also end up short in home games if they schedule 2:1 deals, in which case they end up not only short home games, but short revenue, as they miss the big payday.
This is not a new problem. Look at some schedules from the past:
1970 3 home games, 6 road games
1979 4 home games, 7 road games
1984 4 home games, 7 road games
1988 4 home games, 7 road games
1989 4 home games, 7 road games
1996 4 home games, 8 road games
2006 5 home games, 7 road games