Rudder is only used to maintain balanced flight. That doesn't mean using more rudder than, as gemini76's instructor told him, is required to prevent yaw.
Just keep the ac in balance, that's all. "When a wing drops during a stall, yaw must be prevented by application of opposite rudder" means the same thing, in my opinion, whereas an overenthusiastic hoof full of top rudder may well cause an incipient spin in an unexpected direction! But use of aileron in the stall is fundamentally incorrect and, in some SEP Class aeroplanes, will certainly cause significant undemanded roll rates - the classic hallmark of an incipient spin.