Not sure why the Networks decided all games have to start at Noon or 3:30 - some of the night games have 6 or 7:30 starts - The day game times need to be spread out.
3 time slots to (hopefully) get in 3 full games. And, by the way, not everyone lives in the Eastern time zone. I think it’s the ACC that runs slightly off schedule.
Most of the major conferences are on the ABC family; CBS has the SEC, and NBC has Notre Dame. Fox has the Big 10.