As the regulars on here know, I am truly a reservation guy. We like to spend our time seeing what we go someplace for rather than be chasing from park to park (if there are more than one in the area) finding a site. Or if they do have one it is very tight, next to the dump station, etc.
And, if you have to cancel, the price is cheap compared to the potential time consumed, added cost, etc.
It also depends upon you desires - we tent camped for decades before we started RVing - now we like FHU.