Iterative Delivery & Flow
Agile teams depend on steady flow and fast feedback to deliver value early and often. These laws reveal the dynamics behind queues, delays, and diminishing returns, helping teams understand why work stalls, how to maintain sustainable pace, and when progress is merely an illusion. By applying these principles, teams improve predictability, reduce waste, and build systems that support continuous, iterative delivery.
| Concept | Agile Relevance | Usage in Agile |
|---|---|---|
| Little's Law | The average number of items in a system equals their arrival rate multiplied by their average time in the system. | Used in Kanban flow optimization, WIP limits, and throughput tracking to increase efficiency. |
| Boehm's Curve | The cost of fixing defects rises exponentially the later they are found in the development cycle. | Reinforces Shift-Left Testing, Test-Driven Development (TDD), Continuous Integration (CI), and automated testing to catch issues early. |
| Kingman's Formula | Queueing delays increase exponentially as system utilization approaches 100%. | Encourages Agile teams to control Work-In-Progress (WIP), maintain buffer capacity, and reduce variability to improve lead time predictability. |
| Ninety-Ninety Rule | "The first 90% of the code accounts for the first 90% of the development time. The remaining 10% accounts for the other 90% of the time." | Highlights the risk of underestimating complexity and the illusion of early progress. Reinforces the need for clear Definition of Done, incremental delivery, early integration, and Agile engineering practices to avoid last-minute bottlenecks. |