It really depends. I am a pet groomer, and people bring their cats to us anywhere from every 4 weeks to once a year. I personnaly do mine 2 times a year. Long hairs need more grooming obviously than short hairs and those that go outdoors would need bathing more often as they would get into more dirt. So unless they get into something that NEESD to be washed out, I think every 6 months is sufficient.