Rather than consumerism gone mad, experts point out that we intuitively adapt other elements of our beauty regimes dependent on our needs. For example, body moisturiser is switched due to weather and a heavier eye cream is favoured after a late night.

For hair stylist Bumho Lee, it makes perfect sense. His fellow Koreans have had intensive 10-step skincare routines for decades, and the skin on the scalp is, after all, simply an extension of your face. “Typically, Koreans like to shampoo every day, so the trend is to have a variety of haircare products on hand and choose what you need based on how your hair feels that day,” says Lee.

Even those with sensitive scalps can indulge in shampoo switching according to consultant dermatologist Dr Vicky Jolliffe: “Because shampoos are rinse-off and have very low allergenic qualities, it’s rare for people to have reactions to them as they’re so extensively tested.” This isn’t a case of washing your hair more though. Those who lather-up once a week need not suddenly start washing their hair daily, it’s more a case of assessing your hair’s needs when you do wash it.

Afro textured hair, for example, often needs to be washed only weekly because the tight coil of the hair (even if it’s been relaxed) means there are more points at which it can break when wet. But assuming that it is dry, every week could be an error, says Charlotte Mensah, artistic director of The Hair Lounge and afro hair specialist. “Although afro hair tends to be dry, using the same shampoo for months means it can become less effective, especially if the hair is coloured and needs a specific shampoo to help maintain that colour. If it’s fine, it can be weighed down by heavy moisturising agents in shampoos too.”

The surprising reasons you should be using more than one shampoo