Following the seminal work of Brainard, 11 a case for gradualism can be made in the context of the uncertainty inherent in economic data, models and parameters, notably in times of unconventional monetary policy.
In the absence of perfect or complete knowledge about the way market participants will react to the announcement of monetary policy adjustments, and about the way those uncertain reactions will transmit to our objective, it may be optimal to adjust policy more cautiously and in smaller steps than if we had 7 / 13  BIS central bankers' speeches  perfect knowledge.