Should Six Sigma start after Lean Implementation?
My perception to Six Sigma is that it should start after Lean Implementation, at least basic (Stability Phase and Continuous Flow), then can go in parallel, since Lean helps set the standards and Six Sigma controls deviation from standards.
But the DMAIC problem solving methodology can be simplified as the PDCA from the start of Lean Implementation. The certification process of Black / Green Belts is a rigorous part of the subject that I hope to be spread to all operations management consultancy fields.