In most aspects of my life, I am a plodding planner. And that is how we started out in the early days of our RV travels, in 2005.
Gradually, we stopped making reservations for the whole trip.
Finally, we stopped making them at all. This enables us to change destinations at the very last minute, due to weather or health or whim.
So we have been "winging it" for about nine years now, with no problem.
But there is a catch: first, we travel mostly in the West, where there are more campgrounds (I think) than back East.
And second, there are times when we are entering a large urban area, it's three pm, and we want to make sure we get a site. So we call ahead and make a "late in the day" reservation. (This is on longer driving days, when we are not sure where we are going to be at the end of the day.)