Is Lean in a Job Shop a Square Peg in a Round Hole? Lean is an immensely popular methodology for improving performance and reducing costs is manufacturing environments.  The problem with lean as encompassed in the Toyota Production System is it was designed for a mass production manufacturing and not a job shop.  Although there are some tools like identifying waste that are useful, most are not.  And the basic premise of reducing inventory is not applicable to job shops that have little inventory.