Here is the description of the product from the Sephora website, "Over time, hair becomes accustomed to products that are used on a regular basis, resulting in build-up. Shampoo d'Alternanza serves as an alternate shampoo for removing hair build-up deposited by cleansers, conditioners, styling aids, or other external conditions such as chlorine or salt water. The unique formula also provides ample nourishment, naturally hydrates hair, and adds new dimension to the hair shaft. Derived from plant extracts, vitamins, and wheat proteins. Shampoo d'Alternanza not only rids the hair of residual build-up, but does so without stripping hair of its vital nutrients".
First thing, Sephora should have known better than to write this misleading description. Hair is dead, it cannot become "used to" any product. Product builds up on the hair shaft and that is that. Otherwise, I do think that this is a great shampoo. I use it once every two weeks and so far, the bottle has lasted me for ages. It doesn'y overdry my hair but it still manages to clean everything excess out of my hair.
I once had someone say something to me about using a deep cleansing shampoo on my dry hair. This is why I do it, when product builds ups then my products can't penetrate correctly. We all know that. However, products that are designed to hydrate or defrizz hair tend to build up much faster than those that are not so clarifying shampoo is even more vital for users of these types of products. Also, when the conditioners can't pentrate correctly, they don't hydrate well enough so hair is actually drier. So yes, clarifying shampoos are also recommended for those with dry hair. You will want to follow it up with a deep conditioner to reap the highest amount of benefits.
photo courtesy of Sephora