6S to improve
Preparing for the presentations I found some 'areas for improvement' in 6S methodology:
Although 6S highlights the need of training for staff, it is very strict and schematic. However effective the training can be its main drawback could be lack of learning opportunities for employees. They are taught tools and techniques which are expected to use but there it is assumed that no feedback from them is necessary.
Secondly because of the concept of green and black belts the organization becomes structured and strong hierarchy is created. This in turn limits people to act as all actions have to be approved by their supervisors and managers.
Although the companies which implemented 6S had had outstanding results of performance with savings of millions of dollars/ pounds whatever the methodology seems to be very complex and one cannot take it for granted the success (while costs of trainings are significant).
If you found some more, please write them and we'll collect them :)