of Walter Shewhart, a quality expert at Bell Labs who proposed a series of short “plan-do-study-act” (PDSA) cycles for quality improvement. Project Mercury (1958-1963) ran with very short (half-day) iterations that were time boxed. The development team conducted a technical review of all changes, and, interestingly, applied the Extreme Programming practice of test-first development, planning and writing tests before each micro-increment. They also practiced top-down development with stubs.
abstract principles and concrete practices (for one small team). LeSS hits a sweet spot balance between defined concrete elements and empirical process control (for large groups). LeSS is Scrum applied to many teams working together on one product.