Backswing Timing by Mark Crossfield

Mark Crossfield responds to this interesting question from Pete Byard on social media, "Any Tips for controlling timing on back swing?" 

Mark isn't really sure if this is something you can work on or if it will actually help your swing. It is very player specific and could mean a wide range of things from, a fast tempo, taking the club away quickly or slowly, a fast transition from the top for example. What are your thoughts on this, how does temp or timing help you and how do you improve it?