Only time I have done it (2 or 3 times) was when a group of friends and family (total of 4 families each with kids) were meeting for a weekend and the way the campground was laid out, 5 sites were clustered together and we all chipped in extra for the fifth site figuring we could spread out campers better and have a bigger " common area". Plus, it could have potentially been an akward situation if 4 of 5 sites everyone is together and then there's just you right next to them. I've been that guy and it was no fun