The fundamental problems with mass (or “batch-and-push”) is that each process in the value stream operates as an isolated island, producing and pushing product forward according to schedules it receives from Production Control / Work orders instead of the actual needs of the downstream “customer” process.
As a result, while the value-creating time for producing one product is very short, the total time that product spends getting through the plant is very long.
While it is good to be aware of waste, the future-state designs need to eliminate the sources, or “root causes” of waste in the value stream. The most significant source of waste is overproduction which means producing more, sooner of faster that is required by the next process. Overproduction results in shortages, because processes are busy making the wrong things.
Rother, M. and Shook, J., Learning To See: Value Stream Mapping to Add Value and Eliminate Muda. © Copyright 1999 Lean Enterprise Institute, Inc. Cambridge, MA., lean.org. All rights reserved.