Hmmm, I'm not sure. I've used it as both a RO and a leave-in and have never noticed any build-up. I don't co-wash, but I low-poo with the Shea Moisture Coconut & Hibiscus shampoo and have never had issues.
I know some will disagree, as for quite a few here Shea Butter can build up. Just, in my experience, it's never been an issue