I'm a no belt, have attended an all day Lean class, and completed all the company required online training (Maybe a dozen short courses). I've taken part in a few Kaizens. One was for DC-10 engine change. We observed, and documented the entire process, then devised ways to streamline the process. The spaghetti diagram, alone, was shocking. We knew there was waste, but no Idea of the actual amount. As a result, several engine change kits were developed that get wheeled out to the aircraft at the beginning of an engine change. We have made numerous similar improvements.