We full-timed and traveled constantly for 16 years and rarely made reservations. The key is to be flexible, pull in early in the week and early in the day and don't limit yourselves to full hookups. Our first choice is always a public park - national, state, COE, national forest, county and city.
For the 3-day holidays we don't go where the vacationers go. We'll find a nice quiet place not near any water - lake, stream. We let the working folks have their fun. We go to those places when they leave.
Even Yellowstone and Grand Teton Nat'l Parks have plenty of campsites that aren't even reservable. Again, you need to be there early morning to get a site. Stay nearby the previous night.
Someone mentioned that you must have a big RV and that's why you want full hookups. I really don't understand that comment. Big RVs have large holding tanks so they definitely don't require full hookups. . just the opposite. We love boondocking with our 40' motorhome and our tanks can last 12 days.
It can be done. We could never do constant reservations.
