Your right about using the pool, maybe a yellow flag upon a valid complaint, the passenger whom is not located in the pool area can then go to pool attendant to have the yellow flag removed.
If the yellow flag is present after 45-minutes, a red flag can be placed on the lounge, so the past passenger can go to security to claim any personal items.
In most cases, passengers place personal items on lounges close to the pool early in the day before most passengers get out to the pool.
You will find that one person will save a majority of a section of lounges in a prime location and fellow group members will show up an hour or two later.
Around noon time, there will be little chance of saving lounges.