I try to pack the nesting boxes as full and tightly as possible. Otherwise, when the ladies go to lay an egg they end up knocking a lot out. As for the floor, I just do enough to cover it. After all, they're just using it to poop on! Also, I live in Texas and it doesn't get very cold here (in San Antonio at least), so I'm not using it for them to stay warm. If it were cold you might want to add some additional hay to "trap" in the warmth. When I first started I know I was using a lot more hay than I am now. More hay = more trips to the feed store = more money. You'll find what's right for you once you've been doing it a little while.