I'll trust myself. I actually listen when I have heard the committee chair speak for the past dozen years, and when they bring them in on CBS or ESPN on a Friday, Saturday or Sunday. They also have mock selection days for the media in February, where they show their process.
They are quite open in saying that most things are done by Friday. But they have also been quite open on the loose ends that need to get discussed on the weekend, and will often state a certain result changed the #1 line on the weekend. It's not a mystery. They openly state it. Just listen.
IIRC, They had a 2 hour discussion on the #1 in 2014 when Virginia got it on Saturday, and discussed it again on Sunday. I wasn't in the room. But you know how I know? Because the chair told the world that is what happened,