When I told DH I was setting up the covered litter box as a nest box, he said it was too small. It was only there a couple of days before my pullet decided it looked like a much nicer place to lay her eggs than the dog igloo she'd been using up to that point. Its pretty cozy but now I have two laying in it every day.
I think my girls like the nesting boxes with a little more room but with three of my silkies brooding in the favorite spots the rest are not opposed to climbing in on top and dropping it on their heads.
I watched as one was laying and did just that and when Duffy (silkie) saw the egg she just rolled the it under her and proceed with her brooding. Did not skip a beat. They are funny funny to watch.
I have three all 12X12 and in a row. They always lay in the one on the right where I walk up each day. Yesterday there were 6 eggs in that box and no others. They all seem to share the same one each day. Every now and then there will be one in another box. I guess one of the girls couldn't wait for another to get out of their favorite box.