If it works the way it has at the resorts, and in the way it will for the UK sailings as shared by
@BadPinkTink, there will not be a reserved amount of time. When you want to go to the pool, it may be available right away and you just go. At some point the pool might reach capacity and then you would add your family to the queue and would be called when space is available. Once you are at your pool space, you may stay as long as you like, but if you leave the pool deck, you would have to queue up to return. Now, before someone says "what if I need to go to the bathroom, get a slice of pizza, get a book from my stateroom", these would be handled in time increments just as they are at the resorts. A 5 minute trip to the bathroom or your stateroom, no problem. Going to sit-down lunch at Cabanas? You will need to check the queue.
In our experience, this type of process has worked very well at the resorts. There is distance between groups of loungers so you are more spaced from people that are not your party. Once you have your space, there won't be anyone just lurking and waiting for you to go to the bathroom so they can move your things and say they thought you left. And, if you are a family that likes to go to the pool first thing, all of the loungers won't be "reserved" with towels.