I have found they will lay anywhere they think is a good spot. You can provide the most wonderful nest box setup ever, and they could still choose to lay on the floor right underneath the roost. My hens are young and still figuring things out. It can take several months for them to figure out that the nest box is for eggs, even with the dummy eggs in there to show them. The point is, don't worry too much about doing it the 'right way' or the 'wrong way.' All that matters is if the chickens think it's a safe and comfy place to put a potential baby. I have one hen that insists on laying in an old tree stump with shoots sprouting out of it with about a decade of leaf litter to sit on. She's completely shield from view when she's in there, and it's a pain to duck through all the stuff growing around it, but she has laid a perfect egg every day for the past week and she's only 20 weeks old.