To Get To The Root Of A Hard Problem, Just Ask “Why” Five Times In The Lean Startup, Eric Ries argues that returning to the question of why five times cuts to the quick of a problem. To Get To ...

This changes the 7 wastes of lean to the 8 wastes of lean. The original 7 wastes were described by Taiichi Ohno, the Chief Engineer at Toyota, as part of the Toyota Production System (TPS).