Do we consider Places for potential characters as we go? Isn't that a lot of work?
Well, there are a few reasons. Just like Places demonstrate who a person is to our viewer, they also can offer the storyteller clues when we're getting to know someone as well. For example, perhaps you go to a potential character's office to chat as a pre-interview. Perhaps he's a pretty straight-laced guy, and he's having trouble opening up about more than just his company. But then, when he gives you a tour of his workspace, there's a photo of him in front of the Eiffel Tower with his wife and kids—showing you that travel, and family, be things to ask about and see if they bring out any of his Big 3 Things. Or perhaps he has a comic pinned to his bulletin board that may suggest a sense of humor that's inconsistent with his public persona.
In addition, if you're only listening for the Big 3 Things in your pre-interview, then you may miss important information about their story that may help inform your Purpose. And if you're only listening for the Big 3 Things, then when you develop your Purpose, and choose your Heart, you'd have to go back, and pre-interview the chosen Heart again, to be able to make any progress in constructing their story before production.
That's why, in the listening phase, we want to be mindful and take note of potential Plot Points and potential Places. So that when we move to constructing our story, we save time and can move forward immediately on constructing our story. But also so we can get a complete picture of who a person is.