The 5 Whys tool is versatile and is used in a lot of places. After a failure is a great place to use it to try to understand why the failure took place. In the Analyze Phase of DMAIC, it’s a great companion of the Fishbone or Cause & Effect Diagram in order to push past brainstormed symptoms to potential root causes. I’ve also seen it used in the Lean Agile process to better understand customer requirements. Five-year-olds aren’t the only ones who have discovered a fabulous tool!