Don't forget that many crew members don't have time to go out to the pool, it is mostly the more..."privileged" workers, such as those in the kids club, entertainment areas, etc. that have more free time. So no, just because there's a crew pool doesn't mean all the crew members use it.
clairedy6,
Don't forget that all CM's on the ship can work up to the max 92 hours per week and those include the chefs, sous chefs, pot washers, yellow suit guys, servers entertainment crew, kids club ent's team.
Those that chose to use to use the pool do so, those that choose to sleep, work out in the gym do so, those that choose to go ashore do so.
Whether they choose to use it is up to them, the 72 hours off per week (if working the DCL SET maximum of 92 hrs) is up to them!