Maybe every week or two with conditioner, and usually at least a month or more between shampoos...I've gone probably a good 5 or 6 months without shampooing before. My hair is very dry and doesn't really get greasy, so I can go a long time with just water, ACV or conditioner on the ends. Sometimes I really do feel like getting that deep clean, though, and it does feel totally different when it's shampooed/conditioned. I just don't like doing it too often, it wrecks my hair.