Does the shampoo matter? Yes. Why?...
There are two major types of shampoos (professional and nonprofessional) and a few sub classifications.
Nonprofessional shampoos: there are two major sub classifications of this type, Stripping Shampoos and Coating Shampoos. There is no benefit from either shampoo, and in fact they will over time degrade the state of your hair...
Stripping (clarifying, dandruff) shampoos strip the hair using a detergent with a neutral pH (7) opening the hair cuticle and cleansing the inner part of the hair. The upside is they will remove product build-up, metallic and mineral residue from hard water like chlorine. The down side of this is with out something to close down the cuticle layer the hair cuticle will remain open and the hair will dry out from evaporation, thermal drying etc. over time reducing your hair to nothing more than a dried out shell. This will cause a dry feeling to the hair; making it tangle prone, and leaving the hair susceptible to breakage. Also if the detergent is strong and you exfoliate the scalp with out using something to hydrate the pours on your scalp, you can end up with oily scalp as well because your sabious glands will over produce oil in their job to keep your head conditioned.
Coating shampoos (two in ones) coat the hair due to a waxy type of substance within the shampoo the coats and seals the cuticle layer from the inside out. The upside is immediate, resulting in fuller feeling, shiner hair. This is only a short-term fix. The down side is than your hair would then be sealed with a non-water soluble solution that builds up not allowing your hair to breathe and hydrate causing your hair to dry out from not receiving any nutrients and will over time reduce your hair to nothing more than a dried out shell covered in wax.
Professional shampoos: I have found three types of these shampoo sub-classifications, Good, Better, and the Best. Depending on the date they were originally formulated and the technology used in the creation of the shampoo without using names it simply stands to reason, if a shampoo was formulated in the 60’s or 70’s vs. a shampoo formulated in the 80’s or 90’s the newer shampoos would stand a better chance of being technology current. Research into any of these is a good idea, ask your local stylist about what shampoos may be right for you…