I am sorry MvMac, A bit stupid of me to drag BC into the conversation.
Point taken about TW swing. At key 3, to far forward, could you compensate it by extending more? Raising the handle?
Furthermore, between the thumbs. In general at top sport level, if a coach would want a swingchange, how long would it take to have an effect? Or isn't there a rule? It depends on the athlete?