You should have as many litter boxes as there are cats. I've actually also read that you should have as many litter boxes as there are cats plus one. Not all the litter boxes should be in the same place, either depending on the cats. When I had multiple cats, I made sure to have enough litter boxes for them to give them options. Some days, they wouldn't use one of the litter boxes at all, and other days they would. But, because of what I read about litter boxes, I kept the litter boxes out for them to give them options.
