Therefore, the information flow is only in one direction, and it is not until the end of the chain that errors, changes and corrections can be relayed to the start of the sequence, causing estimated costs to be under predicted.
This can cause many problems; such as time consumption due to many modifications being made as each stage does not take into account the next.
This method is hardly used today[citation needed], as the concept of concurrent engineering is more efficient.
Traditional manufacturing has been driven by sales forecasts that companies need to produce and stockpile inventory to support.
Lean manufacturing is based on the concept that production should be driven by the actual customer demands and requirements.