Wells made the point that the setting controls what characters can see or do and lets you control the flow of action as well as setting the mood or just being there.

Taverns, town wells, Rotary meeting, coffee shops, etc are places where people meet and exchange information. Bridges, gates, mountain passes, and intermittent wormholes control when and how people can get from one location to another.

The servants who travel the back corridors in the castle are likely to know more than the courtier who stays in the main hall. The traders who know the secret passes can reach our hero faster than the Army. The guard at the city gate knows who comes and goes.

As writers we should take more advantage of the physical surroundings in our story than we commonly do. We let the scene set a mood, and maybe we say to ourself "Joe needs to learn about the murder. Maybe he hears about it in a bar."

We seldom say "The wormhole opens for a day every other week. That means there will be a dozen starships from all over the galaxy lined up waiting for their turn. How will my hero's pirate ship fit in with them? How can he hide? Who will owe him a favor?".

She punctuated her talk with interactive exercises in which we examined a map and determined who had what kind of advantages based on where they would be (gate keepers, bridge attendants, the man in the bell tower, etc.)

She encouraged us to define our setting in terms of how it affects the action. How it limits or eases our character's access to information, movement, essential materials, etc.