The camp site creates a refuge for the player, who can rest there for free and for as much time as they want.
Since Alpha update 30, Camps can now be packed up and will return to your inventory, allowing you to use them again and again. It takes 3 days to establish the camp, 5 to fully rest and another 3 to fold it back. If time is not a factor, it's the most useful sanity-restoring items.
The Camp site makes travelling much easier, and can be good, especially for new, inexperienced players.