Not sure how it will work for the Big 12, but for a 14 team conference, a 3-5-5 schedule makes sense.
3 protected rivalries
play 5 other teams in rotating years.
That way you play everyone every other year.
If we play a couple years it could look like this
ISU, KSU, KU, OU, OSU, TX, Tech, Baylor, TCU, WVU, Cincinnati, UCF, BYU, Houston
ISU - KSU, KU, OSU
KSU - ISU, KU, BYU
KU - ISU, KSU, BYU
OU - OSU, TX, BYU
OSU - OU, ISU, UCF
TX - OU, Tech, Baylor
Tech - TX, Baylor, TCU
Baylor - TX, Tech, TCU
TCU - Tech, Baylor, Houston
WVU - Cincinnati
Cincinnati - WVU, UCF, Houston
UCF - Cincinnati, Houston, OSU
BYU - OU, KU, KSU
Houston - TCU, UCF, Cincinnati
With a 12 team conference, you could go with a 5-3-3 schedule
ISU - KSU, KU, OSU, WVU, Tech
KSU - ISU, KU, OSU, BYU, WVU
KU - ISU, KSU, OSU, BYU, Cincinnati
OSU - ISU, KSU, KU, Baylor, UCF
Tech - ISU, Houston, Baylor, TCU, BYU
Baylor - Houston, Tech, TCU, OSU, BYU
TCU - Houston, Tech, Baylor, WVU, Cincinnati
WVU - ISU, Cincinnati, UCF, TCU, KSU
Cincinnati - WVU, UCF, Houston, TCU, KU
UCF - Cincinnati, Houston, BYU, WVU, OSU
BYU - UCF, Tech, KU, KSU, Baylor
Houston - Cincinnati, UCF, Tech, Baylor, TCU
One year ISU would get Kansas, Kansas State, OSU, West Virginia, Texas Tech, Cincinatti, Baylor and BYU
The next year ISU would get Kansas, Kansas State, OSU, West Virginia, Texas Tech, TCU, Houston and UCF