I must be lucky, I have 4 cats, with only 2 litter boxes. We have a spare room in our house, that is our "Cat Room". It has the two litter boxes, the water dish, and the food dish. We free feed our cats, so when I clean the boxes once a day, I make sure to fill water and food. The litter boxes are used enough, that I believe the litter gets changed (through cleaning), about once a week.