After launching a serious Lean implementation journey, at some point it will occur to you that a significant percentage of the issues your suppliers, trades, and employees identify could be avoided by paying serious attention to plans and product specifications up front. In the ideal world, that’s where you’d begin, but there’s a problem with that: Until you hold the event and show them the money as described in steps 3 and 4, very few architects, designers, engineers, or managers accept the magnitude of the problem.
An additional obstacle is when you begin with plans you often don’t surface the critical process issues that loom as obstacles, no matter how good the plans are. At the end of the day, practicality rules. Moving upstream pays off enormously in Lean, but experience says don’t lead with it.