I applaud the attempt at curbing this. I think it is ridiculous when people come out at 6:45 a.m. and drop a shoe, a book, hat, another shoe, magazine and another book on six deck chairs. They finally come out around 11:00 a.m. and use the chairs for thirty minutes and then go to lunch for over an hour and then come back and sit for another thirty minutes before leaving for the day.
Sorry, but this is a common practice and one I have paid close attention to.
If you need to leave for fifteen or twenty minutes that's fine but if you leave for over a half hour then you've lost your "prime spot". Use it or lose it.