How much does 30+ feet actually effect ability to find space

We have been in state, city, and COE parks where 40’+ would be no problem. And we have been in some where it would be difficult to get 35’ into. Most have some number of longer sites, with many more sites shorter ones. If reservations are allowed, the larger sites go first. Likewise if the park is first come first serve the longer larger sites go first. Waiting til the last minute can be a problem at a popular park.