Lean as a management system
Lean is not about speeding up each workstation in isolation. It improves the overall flow by addressing customer needs, process constraints and variation.
Value, flow and respect for people
The Lean Enterprise Institute describes Lean as a way to create needed value with fewer resources and less waste through continuous experimentation. It starts with the customer's problem and the real work that creates value.
In industry, quality, lead time, capacity and working conditions must be addressed together. A local improvement that moves the problem to design, maintenance or a supplier does not improve the overall flow.