Lean is about one simple thing. Getting more eye balls on the work. People's eyes. Every one of the people who are working on any kind of work (the roots are in manufacturing, but the concepts extend to other contexts) And enabling the anthropologists in them.
That is why Lean is a long journey. It often takes a new manager recruit (and yes even at the executive level) to take around 10 years or more to become integrated well and operational in a company like Toyota. And there is a reason for that.
It takes that long and more to become a trained anthropologists. And help every employee become an observer of their work and work and think like an anthropologist to observe and understand how one's work can be improved. That is why Lean programs which just roll out methods and techniques do not reap the benefits of being able to compete extraordinarily well in the marketplace.
When every employee's eye balls are turned on to inspect the work they do and there is platform to improve that work every day, all day long, you then get an improvement level that is hard for the other competitors in your market to compete with.
That in a nutshell is the essence of Lean.