Exactly this. They want secluded, dark, small protected areas. If they don't lay in the nests try closing them up some to make more inviting. Hearing your set up you should be fine but if they decide not to use them close up the openings to nests more to make them feel secure. Entrance to my nests are 9x9 inches. Each nest in itself is 12-13x12" and will have two birds laying in same box at one time.They will find them automatically, my chickens did not have a nest box so they braved going into the bigger goose shed passed a protective gander just so they could use the nest boxes in the goose shed. They love a nice cosy nest box, probably makes them feel safe and secure at a time, during laying their eggs, when they are most vulnerable to predators