I have 5 with scoopable litter. 3 on the porch (there is a door flap in a window) and 2 inside... 1 guest room and 1 in an abandoned storage closet. I clean them once every other day. I call it kitty litter patrol. The cats follow me to watch the process. I use the same litter for months on end. So it doesn't end up being too expensive for me. I toss the entire thing every six months. By the way, I put a ton of litter in each box, so the initial investing is quite high, but the upkeep low. My cats do select the cleanest box to use - I have watched them jump from one to the other. With two cats, I need that many. The ones on the porch don't get as much use on the cold days. So there ya go. Now you know my deepest secrets about my life as a cat owner.