The wording states periodic; however, if you do training less than annually your institution may face not only criticism from regulators but liability if something goes wrong during a security related event. With security training, I always looked at it more from a perspective of wanting my employees to have the knowledge to help keep them safe rather than as a regulatory requirement. With larger institutions it becomes difficult to do with any degree of personal interaction which is challenging.
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Knowledge is knowing what to say. Wisdom is knowing when to say it.