Sounds like us when we first started 5 years ago. I have everything setup and know exactly what site I want and what dates. No time to browse or think. I've been lucky and get what I want. If it's a major holiday just gotta have a fast computer and clicky finger. A lot of people just reserve sites and end up cancelling. If I'm late to the party and really want a certain campground I just browse A lot at random times through the day and I've been lucky - scored some spots. I start booking in December / January
Forgot to mention we have a 19' toy hauler so I never worry about site length, just get whatever is open if our usual spots are booked. With bigger trailers you would have to know what sites you can book.