As a general rule, how often does oily hair need to be shampooed compared to normal or dry hair?

Oily hair typically requires more frequent shampooing than normal or dry hair. This is because the sebaceous glands in the scalp produce excess oil, which can make the hair appear greasy and flat. Regular shampooing helps to remove this excess sebum, preventing buildup and maintaining a fresher appearance. In contrast, normal or dry hair does not accumulate oil as quickly, so it can usually go longer between washes without looking unkempt. This distinction is crucial for maintaining the health and appearance of different hair types.