A lot depends on your time constraints.
We just did a one-month loop to the West coast and back. We were limited on time and wanted to pack as much in as we could. We also had to be in San Clemente, CA for a wedding on July 4th weekend. This would be our only trip west with the kids most likely. They travel well, so to speak. The MH makes covering ground relatively easy on them.
Holiday weekends dictate having reservations just about anywhere.
We estimated the day we would reach our first "stop" in our tour. We left home on Friday and made the reservation for Moab on Monday. We had reservations from that point until we started our 3-day trek home.
This plan allowed us to squeeze in some extra sight seeing between destinations and know we had a place to land at the end of each day. Otherwise, we would have stopped many of our days short to start the search for accommodations.
For example, at Bryce Canyon on the day of departure for Zion, we got up and moved the RV to the shuttle bus parking lot. We went on a pre-planned horseback ride to the bottom of the canyon, returned to the RV and took off for our Zion area CG. We checked in and took the Toad into the park. We checked out the Visitor's center, did some sight-seeing and planned our next day's adventure of hiking the Riverside Trail on the Virgin River. The horseback ride at Bryce required reservations. There were people waiting standby in the hope to catch a cancelation.
So, some things require pre-planning. Some of the busy parks require reservations. I was worried about deposits and such but am happy to report that we did not miss a single reservation.
Most of the stops were two nights. We had a few single nights and Yellowstone was four nights. This also required us to stick to a plan.
We ended up wasting a day (in our opinions) at Monument Valley. We think we could have done a drive by or single overnight. We stayed two. This could have given us more time at Grand Canyon where we basically did a drive by on the way to our next over night at a family member's house in Kingman, AZ.
If you are retired, take your time and stop early enough in the day to find your next CG. If you are on a tight schedule, pre-planning is suggested.