We almost always make reservations, and have rarely had to make a cancellation. State Parks and Federal facilities seem to be the hardest to find a site in, probably because of their generally lower cost from neighboring, private CGs. It is much easier to get a site from Sun - Thursday, but that can prove difficult in high-traffic areas, such as the Ocean front state parks in SC (one less now that Hunting Island is all but closed to camping). Edisto Beach, Huntington Beach and Myrtle Beach State Parks have significantly raised their site prices, and getting a site reservation in any of these parks now for the late spring - early fall is very dicey.