In our provincial parks (Ontario), you must occupy the site. If you have a seasonal site where you are set up it is different.
I understand people wanting a seasonal site, however I feel that our provincial parks were supposed to be for everyone not for a few who are lucky enough in a draw to get a site. It really bothers me when you go to a northern park that is supposed to be a wilderness park, meaning very few amenities and you see sites set up with little fences around or sheds and large patio furniture set up on a deck. If people want a permanent site then go to a trailer park where you can add all you want.
You can reserve five months ahead but it seems now that if you do not reserve within a few days of the five month deadline you will never get a site. Therefore seasonal sites in a public park should not be allowed.
When we booked our holidays there was only one site available in all of Ontario. We still had to drive 10 hours to get to it.