Probably the best insight I got into what happens at the D1 level was about 4 years ago when I was in the airport in San Francisco and sat next to a table of six Pac10 refs in a restaurant there. They were all transferring planes to different cities to work games.
I walked over and told them who I was and asked if I could just sit with them and listen. They said that was fine, as long as I bought the coffee.
They were discussing various games and coaches they had earlier in the season and I was fascinated by some of their stories. Their stories were the kind you never know of by watching the game on TV or reading the paper afterwards.
It was apparent to me that these guys took their responsibility very seriously, and their commitment to this level was way beyond anything I wanted to get into.
BTW - they bought my coffee.