I suppose the kind of leaves may affect how well they work. For many years I used whatever was on the ground outside in my runs and coops. I'd rake up pine straw, oak leaves, sweet gum leaves, whatever there was and throw it in. About six inches deep. If it started to get soggy or matted I'd throw scratch feed on top and encourage them to keep it scratched up and fluffy. When the first lot of leaves began to break down and thin out I'd throw another six inches in.
Once in a great while we'd get a really blowy storm come through that would soak everything inside. Then I'd go in with a ptich fork and turn it myself to fluff it up. It usually dried out fairly fast.
.....Alan.