Today’s product development orthodoxy is broken. What’s wrong? Companies are pursuing the wrong goals. They maximize capacity utilization, and wonder why cycle times are so long. They strive to conform to plan, and wonder why new obstacles constantly emerge. They try to eliminate variability, and wonder why innovation disappears. They carefully break processes into phases and gates, and wonder why things slow down instead of speeding up. Ironically, each of these actions actually hurts more than it helps.
We need a different approach, one based on solid economics and real science. The heart of this approach is FLOW, and the enemy of flow is the invisible and unmeasured queues that undermine all aspects of product development performance. Stagnant piles of idle work lengthen cycle time. At the same time, they delay vital feedback and destroy process efficiency. Yet today, these queues remain unmanaged. Ninety-eight percent of product developers neither measure nor control their queues.
But, how can we manage these queues and achieve real flow? It takes a bit of science. We can start with the ideas of lean manufacturing. Then, we must recognize the vast difference between the stable world of repetitive manufacturing and the high-variability world of product development. A product development process must thrive in the presence of variability. Ultimately, we must reach even further, drawing upon ideas from the Internet, transportation systems, computer operating systems, and military doctrine.
This is the first book that comprehensively describes the underlying principles that create flow in product development processes, principles that have produced 5x to 10x improvements, even in mature processes. It combines a lucid explanation of the real science behind flow and a rich set of practical methods. Its underlying principles are organized into eight major areas, focusing on practical methods to:

• Improve economic decisions

• Manage queues

• Reduce batch size

• Apply WIP constraints

• Accelerate feedback

• Manage flows in the presence of variability

• Decentralize control

Nobody is better suited to explain these ideas than Don Reinertsen. In 1997, his landmark book, Managing the Design Factory, first introduced the ideas that have become known as lean product development. His two previous books, Developing Products in Half the Time and Managing the Design Factory, have become required reading for all product developers. For over 25 years he has been recognized as a leading thinker on product development issues.
This book begins where other books on product development end. It is guaranteed to change the way you think about product development. The Principles of Product Development Flow is destined to become another product development classic.