One disadvantage I can think of to a community nest is if you want a hen to go broody in there and hatch chicks it could get messy during hatch.
Occasionally I get a hen that wants to lay somewhere other than my nests. I made a couple of my nests so I can lock a hen in there, which has come in handy for different things. One of those is when I catch her on her other nest to lay an egg, I lock her in the nest I want her to use until she lays her egg. Once is usually all I have to do this to retrain her to use a nest though I’ve had to do a few hens twice.
Another way I use those lockable nests is when I see a hen in there laying, I can lock her in and remove any other eggs that might already be there. That way I can tell which hen is laying which egg. That comes in really handy when I’m evaluating pullets to see which I want to add to my laying/breeding flock and which go to the freezer.
I like my lockable nests and I let my broody hens hatch and raise chicks with the flock. For those reasons I prefer individual nests. But I think you should do what is most convenient for you and how you manage your chickens. I think people care about this a lot more than the chickens do.
