A list without any context! This is so unique that we only see two threads like this a week.
Observing these lists, some patterns emerge, which are dependent upon the author's wishful desires. From these some rules about these lists emerge:
1) The list must be just large enough to include the school the author roots for
- e.g., VT or NC State fan will have their list expand P2 just enough for their school to be included
- Oregon State, San Diego State, Boise State, Memphis, South Florida fan will extend P4 just enough to include their school
- App State, UNLV or Marshall fan will have an even bigger collection to include their school
2) The number must be some perfectly balanced symmetrical even number
- preferred are 3x 24, or 4x 20, or 2x 32
- must satisfy OCD need for perfect symmetry
3) Finances are never mentioned whether it applies to:
- who is paying the conferences for this
- the school's ability to fund Football at this level
- Economic and political incentives necessary for P2/P4 are ignore or passed over.
Number three is in part to justify number one, allowing their favorite school in, but mostly because this would require some research which could lead to an unravelling of their model. There may be other rules in making lists, but these are the three that immediately come to mind and seem self evident.