The Deming Cycle or The Plan-Do-Check-Act (PDCA) model is a proven framework for implementing continuous quality improvement. It originated in the 1920s with Walter A. Shewhart. These four steps provide the framework for continuous improvement. The PDCA cycle basically starts with a plan and ends with an action in accordance with the information learned during the process. In later years Dr. Deming actually changed the Check portion to the term Study to highlight the creation and validation of new knowledge during that portion of the cycle.
The video may be a little fuzzy, this is the slide deck that was used.
A fundamental principle of the scientific method and PDCA is iteration. Once a hypothesis is confirmed (or negated), executing the cycle again will extend the knowledge further. Repeating the PDCA cycle can bring us closer to the goal, usually a perfect operation and output.
Detailed long-term planning cannot meet the rapid changes occurring in the market place and is falling out of favor. Rapid cycles found in Agile software development are becoming more common. The reason is that most successful sales cycles meet market needs by having a high degree of flexibility and the ability to adjust their plans as needed. So, with iterative cycles the rage, is there any need for a planning stage?