It’s as simple as that. Get good at those three things, and everything else about Lean comes much more easily. It’s like having a strong, healthy back. When you’ve got that core strength, you can build on it, do more, and try more complicated things. When the core is weak, even attempting some seemingly basic tasks can be brutal.
Imagine trying to implement kanban without having the rigor to follow the process, or keep things properly labeled and in their right spots. Imagine trying to create flow without standard processes to provide stability. Imagine trying to improve lead time when you don’t have any idea about what work is in progress.
5S. Standard Work. Daily Management. Strengthen those three things, and the rest comes easy.