Cycle time variation is a metric and philosophy for continuous improvement with the aim of driving down the deviations in the time it takes to produce successive units on a production line.  It supports organizations' application of lean manufacturing or lean production by eliminating wasteful expenditure of resources. It is distinguished from some of the more common applications by its different focus of creating a structure for progressively reducing the sources of internal variation that leads to workarounds and disruption causing these wastes to accumulate in the first place. Although it is often used as an indicator of lean progress, its use promotes a structured approach to reducing disruption that impacts efficiency, quality, and value. 
Progress in manufacturing is measured by the production of high quality goods. The unit of progress for Lean Startups is validated learning-a rigorous method for demonstrating progress when one is embedded in the soil of extreme uncertainty. Once entrepreneurs embrace validated learning, the development process can shrink substantially. When you focus on figuring the right thing to build-the thing customers want and will pay for-you need not spend months waiting for a product beta launch to change the company's direction. Instead, entrepreneurs can adapt their plans incrementally, inch by inch, minute by minute.