I bathe Sandy every week or week and half. But I also wipe her feet every time she comes in from a walk (the equivalent of taking her shoes off-I live in Japan). She is brushed out daily. I use a good shampoo and conditioner during the bath and a body spray between baths to keep her smelling good.
Ripley is bathed once ever 2-4 weeks. We use a really good, mild shampoo, so it does not strip the coat of all oils. She always smells great and feels clean. My thought behind it is would I like to be stinky and muddy all of the time? I like to treat her like I would like someone to treat me if I were in her position