Thread: Number of litter boxes

Hiya,
We've just gotten another MC, a lovely two year old girl who's an utter sweetheart. We brought her home Saturday, but since I was trying not to get my hopes up before meeting her we didn't really have things well prepared at the house. We've taken the cat carrier apart and have been using that as a second litter tray, and it's been working well but obviously is not a long term arrangement.
I've read that the number of litter boxes you need is one for each cat, plus one. That seems excessive. For those of you with two cats, is it necessary to have two (or god forbid, three) boxes? The cats are getting along very well and are using each other's litter anyway. If I keep up on the cleaning I really can't see it being a problem just having one, but wanted to hear your opinions.
Many thanks!