Punkin starts to get greasy after 4 or 5 days and smelly doggy. We've been bathing her every week or so. The vet just told us that it's waaaayyy too much and that every 6 months or so is good. She suggested rubbing her down with a wet wash cloth every couple of weeks.
Ewwww - we might be able to stretch the time in between, but I don't think we can go half a year!