I, like so many others, have had the same experience. Not knowing if we fit in the spaces assigned. In some parks, it is even more frustrating when the site is not specifically reserved. So, in other words, a person with a small rig has a large space, and a person with a larger one- well it is tough luck.
The measurements of the sites leaves one wondering also. For example, there is a federal site we go to. It got to the point where we took a measuring tape and specifically measured each site. It became necessary because sites were listed as being 30 feet long, when they were 40 foot or longer.
So what is the solution? Don't have one except going there first or asking people what the place is like.