One of the most popular essays on lean-essays-blog, "Grown-Up Lean" examines how lean thinking has matured since the Poppendiecks first introduced it to software. Reflects on what "grown-up" application of lean principles looks like after two decades of adoption — moving past mechanical application of practices toward genuine internalization of lean mindset principles. Published 16 years after lean-software-development-agile-toolkit-2003, it represents mary-poppendieck's mature perspective on the movement she helped create.