Executive coaching has become an indispensible resource for many senior executives, and can remain in place for many years.  A typical first engagement is 12 months and reflects the need to impart a great deal of information as quickly and efficiently as possible.  Some organisations engage in 6 months blocks, with at least one review point to formally check on progress.  Shorter programs are possible, and we would rather see a manager who needs the training get at least part of what they need in a timely manner.