Manufacturing critical-path time (MCT) is the time it takes a manufacturer to satisfy unanticipated demand through normal processing.
The typical amount of calendar time from when a customer creates an order, through the critical-path until the first, single piece of that order is delivered to the customer.
It is common sense to think that the longer it takes to deliver an order, the more the potential for waste reduction. It also is appropriate that a new metric for lean involves “time” since this has always been at the root of the Toyota Production System, which is from where lean was derived. One question that does arise is, “Why is there a need to propose a new metric for lead-time?”