Design-in-Process (DIP) is partially finished work. DIP is discussed here as analogous to WIP (Work-in-progress of manufacturing). Partially finished work, incomplete work, inventory are considered as waste in IT industry which is not visible as in the manufacturing industry.
In Software development DIP is inventory, which is a risk. As Donald (Don) Reinertsen mentions in his book, queues cause development process to have too much design-in-process inventory. Developers, managers unaware of DIP do not measure it, do not manage it. They even do not realize that DIP is a problem. When DIP is high, cycle times are long.
Don, gives two important reasons why product developer are blind to DIP
- Inventory is financially invisible, partially completed designs are not considered as assets in balance sheet and R&D costs are expensed as they are incurred.
- Inventory is usually physically invisible in product development so developers are blind towards it. DIP is an information, not physical object. We don’t see piles of DIP if we walk through engineering department, DIP inventory is bits on disk drive, and we have very big disk drive in product development.
Blind to DIP, increases variability, risk and cycle time which in turn decrease efficiency, quality and motivation.
Reference: “The Principles of Product Development FLOW Second Generation Lean Product Development” by Donald Reinertsen (page 5 & 6)