That itinerary has a couple days at sea, so if I can find a chair to put my stuff on while I'm in the pool, I'll try not to spend more than 30 minutes in the pool.
The chair police aren't targeting people who are in the pool and saving a chair. That's a legitimate reason to keep your things on a pool chair. They're trying to catch people who put something on a chair and then go have a meal in the dining room, or go to a class or do other activities not related to the pool area. Those folks come and go all day and expect "their" chair to be waiting for them whenever they show up. Those are the "chair hogs."