Technically I have two boxes for two cats. But since Shazam is such a big boy, I don't use traditional litter boxes. I got one of those big storage totes and cut a doorway into it for them. I have two of those in my apartment, one in my bathroom and one in my brothers bathroom. They use the one in my brothers bathroom on occassion, but they really love to primarily use the one in my room. It's a pain that they wont spread it out a bit more but... you know... cats.
It's definitely important to place the "cat toilets" so they are in cat friendly locations. I've always heard if they don't like where it is, they will find another spot to go - yikes! This would probably be a good question too - where do you place your litter boxes?
I put all of mine in my bedroom. They're open boxes and with 3 cats a lot of litter gets kicked out, BUT visitors don't see it and vacuuming is easy because it's just one area. It's a new arrangement but I'm glad I tried it.