Are your cats picky about litter?

We haven't switched the litter up on our cats since we got them. They are very much set in their ways, and it's kind of a "whatever works, don't change it" situation. They are not very receptive to changes at all.

However, the one thing with regards to litter that they *are* very particular about, is which one uses what litter box. One of my cats seems to think all the litter boxes in the house belong to her, and will attack the other cat when she is trying to go. The other cat has to try and sneak around the house and use a litter box that's farthest away from the mean one.