My girls lay better/more quickly and use the nest boxes more consistently when I add a few sprigs of lavender to their nesting boxes. The scent and natural oils make them a bit calmer and more relaxed, allowing them to pass their egg in less time. The faster they get in, lay, and get out; the sooner the next hen can have her turn in the favorite box.
I put some in the nesting boxes. HeiHei lays her eggs in there when she's in there. But she loves to lay her eggs inside the jungle of lavender. I've found 7 eggs somewhere in there and there was one time I found 2 in one spot that I've never looked. I don't know how long it was in there, but it didn't float, so still good. I will be cutting more fresh ones to put into the coop, maybe HeiHei will relax more and not pick on the chicks as much, even though the chicks are now bigger than her.