No, the reason being each project is unique in its own way. If you are aware of six sigma tools & methodoligies you will be able to apply all of them in any given project. Adding to this, six sigma black belt plays a role of a facilitator in complex business environment and champions in bringing a radical change at the leadership level. If he/she has a psychology background then he/she can understand the human dynamics in far better way. It is all about changing the mindset first. If that happens, any re-engineering or business improvement can be done.