It may also depend [1] if you are in a RV or towing a trailer with the various turning radius you require, AND/OR [2] the access road into/out of the campground, AND/OR [3] the proximity of trees and structures.
In California many state and national parks have extremely stringent restrictions. For example, an 'open' site at Yosemite's Lower Pines restricted TT length to 24' and we have a 25' TT ~ you'd think, how does a foot matter? So when booking, I entered "24" into the registration form knowing full well that the reservation clearly stated (red ink is theirs) "The maximum allowable trailer length is always shorter than the allowable RV length (due to maneuverability). You are responsible for reading the site alerts and booking a site that will accommodate your equipment. If you arrive to the campground with different equipment than what you booked for, you will likely not fit, and will be turned away.". Daily I checked the booking site and sure enough, a deeper (31') site became available so I snapped it up and released our original booking. After we arrived in the campground, we scouted-out the initially booked site and DH confirmed that it would have been a VERY tight spot to navigate in to; we saw many other campground visitors struggling getting their rigs properly placed even in larger (deeper or wider) sites.