I find myself doing it every 2-3 months. I just put 2 coats of Meguirs Gold Class paste wax on in the middle of March and by the begining of June I bet I have to redo it. But my car stays outside and is blue so the wax has its work cut out for it.
I was just wondering how often people wax. I only did my Toyota twice a year, but I really didn't care about a perfect finish on that car.