Because I have access to plenty of free cedar, I use exclusively, 100% cedar shavings from the moment the chicks hatch all through their life.

The chicks eat the cedar. They do not die. Contrary to popular belief, cedar is not nearly as deadly to chickens as you have been told. Sadly it is also not nearly as repellant to crawling pests as you have been told either. I still have to wage war and be vigilant against mites, lice and other wee beasties.

But the hens like to scratch all the shavings out of the nest boxes then - clunk - drop their eggs on the plywood bottom and break the eggs. So I cut hunks of that cheap rubber backed indoor - outdoor carpet. You know, the gray stuff you put in the porch to wipe your shoes on. A square of that in the nest box provides a bit of a cushion they can't scratch out. No more broken eggs. When they get gross, I huck them out and install new ones. A light sprinkle of shavings under the carpet makes it even more cushy for the eggs.