Traditional Lean (Toyota style) seeks to eliminate variability. In manufacturing, variability is evil. In product development, variability is inevitable. You cannot predict which feature will delight a customer.
High variability is acceptable if the potential economic upside outweighs the risk. principles of product development flow pdf
Reinertsen borrowed heavily from queuing theory. In a system with variability, as capacity utilization approaches 100%, wait time approaches infinity. variability is evil. In product development
: Using cadence (regular timing) and synchronization to manage complex development networks. Fast Feedback as capacity utilization approaches 100%
Before diving into the principles, we must understand the demand. Traditional project management (think Gantt charts and Critical Path Method) was designed for physical construction, not knowledge work. In construction, moving a wall is expensive; in software or hardware engineering, changing a requirement is expensive.