We have 5 hens and 4 nestboxes. Each nest box is big. Big enough for 2 hens to sit end to end with a big gap in the middle 3 of the could sit side by side.
They all, however, have to use the same nest box. They all have to have it to themselves. And they all like to take their time about it.
I'm surprised the neighbours haven't complained about the racket.