I guess I haven't done this, but you have a unit right? We keep all our stuff in the Unit except what we're actively wearing / using. I don't even need a chair for storing those, lockers near the pool or just on the ground near the pool / hot tub has been generally sufficient. Though again, we're not going at busy times so haven't even seen anyone using a chair before.
These usually are describing someone having a towel or maybe a book, not a whole ... IDK even what ... set of stuff.
IDK, for me I feel like this would be like getting a table at a restaurant because you might want a drink sometime in a day and never even actually sitting there. Or reserving an exercise machine. Like, if you're not using it RIGHT NOW, you don't get to save it. I could see the average bathroom break being OK, but otherwise, you're not using the thing, why are you keeping others who would be using it from using it?