Whatever works for all of you is the right way to go. Lilith and Sophie shared a litterbox for over a year with no issues. When I got Henry, I got a box to put in his safe room. A couple of months later, I had to go out of town for a couple of days so I got extra boxes. 2 more for the girls to get to the 1 per cat plus one extra and I got another for Henry. They ended up liking having all those boxes that I just kept them. Henry's out of his safe room and they all use the 5 boxes.I use one scoopfree ultra litterbox for two cats. I know, im breaking the litterbox rules but it works for us in my small 1 bedroom apt. I do mix the litter around everyday. I wipe the exterior all over with lysol wipes and put a new tray of crysyal litter every two weeks. I would not be able to have more than one cat if i could only have a regular manual litterbox.