SEC has the "cross-division rivalry". Some are stupid - South Carolina - Arkansas... did they pair the 2 new-comers Mizzou and A&M ?
Bama has to play Auburn and Tennesssee, so their Bama-Tennessee cross-over game is essential to them.
6 + 1 + 1 means that you rotate through the other division every 6 years. So someone's 4 years in college may not see certain pairings.
If SEC went to 16, and Alabama / Auburn both went to east (Missouri back to West), that may give an alignment where the corss-over could be eliminated.
They could then play 7 + 2 and hit everyone every 4 years.
With expansion, the regular cross-division rivalry changes a bit.
South Carolina - Texas A&M (SC agreed with it, preferred this instead of Ark.; teams never met before in fb; have geographic ends meet).
Arkansas - Mizzou (gives Mizzou in the east division, a border opponent in the west division)
Georgia - Auburn (unchanged - retains big rivalry)
Vanderbilt - Ole Miss (unchanged - Vandy certainly wanted to retain it; others may have complained about usually easier opponents matchup)
Kentucky - Miss. State (unchanged - not border states - but each comfortable with it - some suggested another usually not a very top tier matchup)
Florida - LSU (unchanged - One Les Miles complained why they have it so tough. And, blah, blah)
Alabama - Tenn. (unchanged - 'Bama complains, but does not want to change it).
They changed the orginal system from 2 regular cross-overs plus one rotation. I liked it. But there were some of the same 'ole complaints about who has it easier (or tougher).
For example, South Carolina's orginal cross-overs were Mississippi State and Arkansas. When they went to one cross-over, Mississippi State was dropped from SC's schedule (a developing rivalry with a record of close games). MSU kept Kentucky while SC was dropped.
No doubt, such decisions were influenced by the level of newness to the conference, old cherished rivalries, connecting the extreme geographical ends of the conference, compatibility judgments, big money games for TV, and levels of institutional power.
I do believe Slive has tried to be fair and reasonable in all this, taking in all considerations. They always seem to reach a consensus of acceptance.
I don't want to sound biased, but LSU, Alabama, and Auburn have sounded real petty, at times, about scheduling.
If or when the B12 expands, they should seek to work this stuff out ahead of time, rather than add, then resolve who plays whom. Newbes' shall be told basically what they will need to accept.