An example here would be maintaining a very stimulative policy -- effectively a zero real federal funds rate -- during 1992 and 1993, a period well into the current expansion.
This turned out, in my judgment, to be very excellent policy, though a departure from the Taylor Rule, because it took account of the unusual structural drags that were restraining the expansion and justified maintaining monetary stimulus longer than normal into an expansion. And, finally, monetary policy has to be sensitive to the potential for structural changes to alter fundamental relationships.