I just finished reading a blog entitled “Developing software by the 15% rule”. Any company providing professional services type work, specifically fixed scope work as defined by a SOW runs the same risk as defined in this blog. I would propose that absoluteness of the 15% is far less important than the message the manifesto sends. The manifesto sets expectations, highlights a methodology and provides perspective clients that warm and fuzzy felling. The feeling that you are the authority and you understand the business.