Sorry I am just getting back to you. I usually change them every 3-4 months depending on their condition. The girls will "dig" a comfy spot and eventually the paper lining will show. That is when I change them. If one of them happens to poop in there, it is easy to clean out. They do hold up...
I would say that I change it every 6 months. There is still a light layer of sand left so I scoop it out into the run, scrub the floor and resand.
I use excelsior 13 x 13 nesting pads in my nest boxes. Hardly any mess on the floor like the shavings I used to use...
I currently have construction sand over the linoleum floor in the coop. I also use PDZ raked in. I used to have poop boards to catch the droppings. Too much work in keeping them clean. Took them out and now I just use a kitty litter scoop every day or every other day and pick up the droppings...