I see it a lot too. When they un-rack my boat for "service" There is only three. These are adjustable and swivle. I guess it is OK if they are under a stringer of keel. I have not seen damage to mine or any others in the marina (yet) I would perfer more as apposed to less but then with only three points you cant screw up and put something in the middle that would stick up too far and not distribute the load evenly.