Shampooing every day isn’t only wasteful, it can also harm your hair, according to NPR. Back in the olden days, when waterfalls passed for high-pressure showers, people would shampoo only once a month. That wasn’t enough, but if you shampoo more than three times a week, you’re actually making your hair oilier because your glands need to work overtime to replace the natural oils you’re washing away.
