I think the first time I experienced the effect of a free group talk was in the basement of my dorm during my freshman year of college. The recipe seems to be to assemble a group of 8 to 10 sharp, quick-thinking young men in front of a tv playing something silly, sappy and semi-predictable. You don't want to the material to be too off-putting or too gripping. The best results come when the group starts to make flippant remarks about the speech, actions, character, or likely future twists and scenes in the show. I think that it is very difficult to predict what remarks will be made.
Similarly, a committee with a mission can take unusual turns and leave predictions behind. I served on a campuswide committee to select a pivotal officer whose office is important to all departments and all students. After a year of examining applications, including some with very high level backgrounds, the committee voted to extend the search for another year. Again with the applications, interviews and discussions. At the end of a second year, they voted to offer the job to the interim, acting officer who had maintained the office during the two year process. Who would have predicted that?
An even more powerful source of ideas, new perspectives and hilarity is a conversational-sized group of older people. They often have the breadth of knowledge and the speaking ability plus both quick thinking and wide-ranging backgrounds to put together comparisons, memories, prospects and perspectives that shake up everyone's thinking. People today have read, they have long memories, they have traveled. They are in communication with many others, including those in a different culture. That implies that even wider-range thinking will be available during the coming years.
From a Google search on "increase in centarians":
The world was home to nearly half a million centenarians (people ages 100 and older) in 2015, more than four times as many as in 1990, according to United Nations estimates. And this growth is expected to accelerate: Projections suggest there will be 3.7 million centenarians across the globe in 2050.
