Living with 15 cats WOULD be stressful to me! All those litter boxes that have to be changed!!! I only have 4 cats and 3 litter boxes and there are times that I have to literally give myself pep talks to scoop and dump the litter, wash the boxes and add more litter. I use crystal litter and I flush it, so it really couldn't be anymore easier -- well having the cats do their business in the toilet would be easier -- and never takes more than a minute or two per box, but it can still be overwhelming at times.