Interaction between instuctors and spectators is being emphasized.
In my mind, at least, this is the driving factor behind the format.
These are big topics, you could literally spend a whole day on any of them. Give an instructor a rigid 20 minutes to lecture, and he naturally tries to cover too much ground. You end up a mile wide and an inch deep. And for a given spectator, half of what's covered may not even interest you, and the time and leeway isn't there to request more details on a specific aspect.
We're trying to be more open than that. We have spectators of various skill levels and different interests. The more flexible we can be, the more everyone will get out of it.
Instructors have total freedom to teach as they see fit. They can set up a lecture if they choose and communicate a schedule for their area. But me personally, I'm not preparing a lecture. I'm preparing to discuss whatever I may be asked to discuss within my topic.
My topic is small mountain freestoners. I am preparing info on finding them (maps and lists and all that fun), gear choices, leader construction, fly selection, reading water, tactics, casting (including hands on), etc. I don't expect to go through all of that with any one group. Some of it I may never be asked to cover. But I expect a group to come by and maybe want me to go into detail on how to find the streams, and I'll pull out the lists and maps and show em. Then maybe another group who wants help casting in tight places, and we grab a few rods and step out into the yard.
And other spectators may never come to my station, because fishing small mountain freestoners doesn't interest them. And that's fine. If I had a rigid 20 minute slot, I'm wasting their time, and preventing them from learning more about something they do care about. In this format, I'm not wasting their time, and those who do care about my topic get more individual attention.