Just a quick comment on my observations about laying nests/boxes:
( and my hens may not be 'normal' )
1) I have a double decker 8 hole metal laying nest unit... the upper row is just above the roost level... and my hens very much prefer the upper row!
2) If I have a rooster or troublesome hen that wants to eat eggs, I have found they will search the lower nests, but often 'forget' about the upper level.... Even if there were no eggs in the bottom row, they most often won't go up to the upper row!!!
3) I have 8 nests for approx 50-60 hens... okay, it seems.
4) I wonder if some breeds prefer 'communal' laying... encouraging and bragging!!! But I also think some breeds prefer 'private' and isolated laying... a percentage of my hens seem to prefer to lay in a nest with one or two empty nests between her and any other hen..????
Oh, building laying nests is exciting..... after all, eggs are what we want... and everyone who has heard a hen before and after laying an egg... knows that is when she is happiest too!