A shampoo that promises repair is mostly promising conditioning agents that rinse straight down the drain. What actually changes hair is the absence of buildup and a scalp that is not irritated. Judge on that and the field narrows fast. Hair washing frequency became an identity marker somewhere around the peak of the no-poo movement, which was mostly nonsense. What survived from it is a reasonable scepticism about stripping.

Almost nobody needs to lather the ends, because the suds handle them on the way down. Working the best shampoo into the scalp and leaving the lengths alone prevents most dryness complaints. It also makes a bottle last noticeably longer. The scalp-as-skin framing came out of dermatology and has genuinely improved the category. Treating the roots and the ends as two different problems is the single most useful idea in hair care.

Frequency matters more than brand, and there is no universal correct number of washes. Find the interval where your scalp is comfortable and pick a shampoo gentle enough to support it. The eight below all qualify. There is no correct washing interval and anyone stating one confidently is selling something. Hair type and climate decide it.