Why You Should Avoid Plenary Like The Plague

A struggle in designing a facilitated process is deciding how much time to keep groups in plenary (one large group) as opposed to working in small groups, pairs, or individuals. During design, one person (often your client) may want to use the plenary to advance their own ideas. You hear, "They really need to understand this," and "If I explain it well enough, we could save a lot of time," and "They're smart people. They should just get it." Ultimately, this cheapens the value of others' perspectives. Not only that...  

• ...it drains the introverts. Although introverts are good listeners, listening in a large group of people is exhausting. 
• ...it frustrates the extroverts. Extroverts engage by thinking things through verbally. That can't happen if they have to sit still and be quiet. 
• ...it blocks production. If only one person is speaking, no one else can contribute to the shared pool of knowledge, bottle-necking idea generation. As diversity and inclusion guru Joe Gerstandt says, "One speaker can lobotomize a group."
• ...it fosters social loafing. Plenary puts people back into the grade school mental mode of "chalk and talk:" sitting back, passively listening, getting bored, or checking out mentally. Even after the plenary session ends and group work begins, it's difficult to shift out of this mode and start contributing.
• ...it builds evaluation apprehension. Not many people like being publicly judged. The larger the group, the greater the fear of speaking out. 
• ...it shorts the learning process. Facilitator extraordinaire Nancy Reuscher uses the metaphor of the marathon to describe the learning process. When you're in the middle of running a marathon, you're hating life. You're thinking about the pain and exhaustion and how far you still have to go. When you get to the end, you forget all that and are feeling great at having accomplished something difficult. Someone who's finished the marathon can't drag others who are in the middle of it to the end just by explaining it. They're caught up in their own condition. Everyone has to get through it on their own and in their own time. 
• ...it disengages. By sending the message to be in receive mode, you are tacitly stating that the group's ideas and input are unimportant.

Worst of all, it defeats the fundamental purpose of bringing a group together for a facilitated session. Following Peter Senge's modes for decision making, it takes groups out of the Co-create mode and slams them into the Tell mode. When that happens, it's no longer a facilitation. It betrays the reason they came together in the purpose. It's become a lecture. And high-performing professionals with minds of their own don't get engaged by being lectured at.