I would agree with most every thing you said jlwilliams. My point was to get someone to step outside their individual box, and look at something they may not realize, as they have never needed to realize it. On the other hand, they may not have wanted the information, I may have overstepped my bounds with my past experience, and training.
I suppose what I should have "suggested", was to shoot the plywood at a room distance, say 10 to 15 feet, with the bird shot, and then duplicate the exercise with their preferred buckshot load. They might learn something they didn't know. But on the other hand, if they choose not to, then they have limited themselves voluntarily, and are satisfied with what they know.
With that said, I think it is time I divested myself of this particular thread, as I have nothing really left to add.