Hi Everyone! Please forgive a newbie type question, but how often does everyone change their litter boxes? I was told to have 1 box per cat. I have 4 cats, & 3 large litter boxes. Three cats are Ragdolls, which are very large, & then there is my Sphynx, the beautiful Nefertiti! I scoop every day, & replenish the litter to keep about 3 inches in each box. I completely change it & wash the boxes about every 3 weeks. Is this okay? A lady I work with has only 1 cat, & she said she changes the litter box EVERY DAY. That sounds weird to me. Our litter boxes are upstairs, so they are not right under our noses. I just don't want my house to stink! Sometimes when you live with an odor you don't notice it, but others do!