TL;DR: Lean is about designing systems that make it easy to do the right thing and hard to do the wrong thing. When software like Excel allows irreversible mistakes with a single misclick–and no meaningful confirmation or undo–it violates basic mistake-proofing principles. Better design beats reminders, training, or telling people to “be more careful.” Lean focuses on making it easy for people to do the right thing. We also work hard to “error proof” processes … Continue reading Why You Can’t Undo a Simple Mistake in Excel — and Why Lean Cares About That