Great managers make themselves redundant:
Not as drastic as it sounds! What great managers do is learn new skills and acquire useful information from the outside world, and then immediately pass them on, to ensure that if they were to be run down by a bus, the team would still have the benefit of the new information.
No one in an organization should be doing work that could be accomplished equally effectively by someone less well paid than themselves.
So, great managers are perpetually on the look-out for ' higher-level activities to occupy their own time, while constantly passing on tasks that they have already mastered.