The Notre Dame Fighting Irish went many years without filling up its roster with the full 85 scholarship limit. For various different reasons, fall would come and the Irish would only have 82 or 83 (sometimes less) scholarship players on the roster.
If you’re trying to build quality depth across all of the position groups, you simply need as many good players as possible.
It’s a different story now. In 2018, the Irish came into the season with 85 players for the first time that I can remember. It came after signing 27 players in the 2018 recruiting class, and some roster movement.