In lean implementation in factories or transactional offices, typically, one value stream is considered: the flow from incoming material to shipped product. Starting from that value stream, the non-value adding steps are eliminated or reduced to create more flow.
In lean implementations in product development, however, there are two value streams to consider: the flow from idea to developed product and the flow of creating, capturing and reusing knowledge: the knowledge value stream.
Obviously, focus on the flow from idea to developed product will make your innovation process more streamlined. Focus on the knowledge value stream will enable the knowledge that is created to flow from one project to the other and thus preventing knowledge to be created for a second or even third time using valuable hours that cannot be spent on increasing the innovation content. Experts on LeanPD typically indicate gain in product development time of 30% to 50% when focus is put on increasing flow in the knowledge value stream.