Leadership may be extraneous when dealing with self-managed professionals in routine circumstances. They have norms, values, and operational conventions, that give them self direction. They don't need leaders. They look to reference groups for standards. Norms and professional ethics as well as routines are substitutes for leadership.
Feedback can be a substitute for leadership.
By building feedback into a task, you can reduce the need for supervision. How are leader-subordinate relationships influenced by gender. This is a very important question as women gain equality in the work place. At one time women were told to learn the rules of football and act like men. Real power comes from giving power to others.