Public reprimands are indeed an excellent way to learn, particularly if your manager's objective was for you to learn that he is out to lunch. It is unprofessional, unfair, and very uncool to criticize an employee in front of others.
In fact, the whole notion of reprimands by a manager is strictly old news. At present, it is far more effective and productive for managers to provide their employees with coaching, guidance, and support. The discussions can include some modeling by the manager so the employee can literally see specific ways to improve his or her behavior.
Reprimands tend to generate little more than resentment, defensiveness, and embarrassment, all of which are compounded when delivered in front of a live audience. If the objective is to improve future performance, public reprimands typically accomplish the exact opposite.
One of the most lasting influences on a manager's style is the way he or she was managed in the past. These prior managers served as models for today's managers. In the same way, your manager is an excellent model for you, especially if you are interested in learning how not to manage. In terms of the bigger picture, perhaps it is time for you to check out the newer models.
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