Here in the southeast it depends on where you want to go, and the time of the year. During the Summer if you want a lakefront site, you better reserve at least a couple of weeks ahead of time, after about mid Sept it's not a problem. In the North Georgia mountains, in the fall you better get reservations a couple of months in advance. Florida State parks in the Keys, you have to reserve as soon as they become available 11 months ahead of time.
It is hard to do a spur of the moment lake trip on the weekends during the summer.
I'm hoping they start building some new campgrounds either public, or private. In many areas they are needed.
