Role plays, rehearsals, et cetera, are most critical.
I noted this quote because of a personal interest in communication. I agree with Professor Zimmerman on the importance of role playing and rehearsals. Yet that hour or two costs the time and expense to organize the program, travel time for participants, and the time at meetings spent being late, waiting around, getting the group started, being too embarrassed to participate, etc. And the great majority of those who need these programs will never have the opportunity, due to politics and resource constraints. This training requires no special equipment, resources, or permission, because it only uses everyday experience and human interaction, which we all have.