I have confidence that a guru will be along shortly to list the Regs that include verbiage requiring annual training, but I would also suggest you look at your own policies - they may indicate that your Board of Directors require annual training as well - and if you have access to previous exams - you may find your examiners have "recommended" training on a particular topic - always wise to heed those "recommendations" - because sometimes they become more than a recommendation if not followed and the behaviour isn't addressed.
Good luck!
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My comments are absolutely no reflection of, nor influenced by, my employer - take them at your own risk.