It depends on your hair type how often you should wash it. If your hair is oily it will look better if you wash it frequently and it's not damaging to wash it everyday. But if your hair is course it's better for it to be washed no more than at least every four days, hair of that type would become damaged and brittle as Zeldy said if you washed it more than that. And showering or bathing everyday is not good for your skin, it dries it out.