I agree about its being fine to use cheaper and easier to find products. However, I do think that it makes a difference to be consistent about using CG products, i.e., those without silicones and sulfate detergents. While rare use isn't going to set someone's hair back to Day 1 of their CG journey, it can still have a negative effect on the condition of the hair, and that can be cumulative if used repeatedly.

Baby Fine 3B, low porosity, normal density and elasticity
CGing since July 2008