I agree that there's no reason to get up to 90.
First off, instead of gradually cutting the roster down the league has chosen to do it in one chop from up to max 90 to 53 plus PS.
I'm sure it's hard to keep track of 90 guys anyway much less coach then up to see who emerges. They will have a big kicker/punter tryout, but even that shouldn't take long to evaluate. 80 should be fine.
