That’s the kicker. Let the AI decide.
Look at Step 3 “Step 3: Build story outlines from the factors above”
What if for experimentation you do: “Step 4: Imagine a new story based on this information above that would be happening concurrently during the events of my story that is not directly related”.
Think about this in terms of any historical event. The Count of Monte Cristo took place during 1815–1838. Now when this was occuring the in the book, it’s not like the rest of the world didn’t exist. We can presume there were other people doing other things, such as Charles Darwin on the HMS Beagle in 1831–1836.
If I’m working on a story like you are, or I am exploring known stories like Star Wars a New Hope for example, I will prompt, “Go into detail of something else that would be happening in this story at the same time my characters are doing xyz”. Or “List 10 events that might be happening in this world during the time period my story takes place.”
It’s a writing exercise that you might find in a writing group to have fresh perspective of your story. The AI can then generate different ideas to give you a peak of what the rest of your world is doing. You’re exploring your characters with different traits and perspectives, but good worldbuilding treats the world itself as a character, so why not explore other dimensions of the worldbuilding.
By no means am I saying it’s a requirement, just that it is a fun exercise that might give you more depth of your world.