My take on 99% atemi is that you need to unbalance your partner/opponent right from the very beginning of the encounter and maintain the state of unbalance right to the end of the encounter. So this means that you are in a position to deliver various atemi right through the encounter. Is this what Mr Amdur was teaching?
The point of the atemi is that you yourself emerge from the encounter comparatively unscathed, unlike your opponent. Am I right?