I tend to use about the same, a few tablespoons but I never added oil. Actually no, when I started out CG I smooshed in Smoothie, oil, gel and all kinds of stuff in my hair all at the same time. Not good! lol. I have since figured out what works, but I never got a hair analysis. I think it could just be a useful guideline rather strict rules. If the protein product seems to help, I say go for it. My hair loves protein, and is generally ok with most other "problem" ingredients. Glycerin is my enemy though, and too much aloe makes my hair tangled and brittle. Also takes forever to dry!!
So the Smoothie as a rinse out when co-washing with something else that is lighter. It would be WAY too much moisture on its own. I also love the smell!!
I am not sure that I'll repurchase it either, especially since Jas put the bug in my ear about the Milk. I don't *need* the Smoothie as a rinse out, that is just how I ended up using it because it was there. So if you have it, I say give it a try