Rule 22 of 24 · Chapter VI — The World Serves the Story
Build only what the story will touch
Why this rule exists
A world is not the point; the story is, and a world built lavishly in every direction while the story starves is a common and seductive failure. It is far more pleasant to draw maps, name kings, and invent calendars than to make a scene work, which is exactly why worldbuilding so easily becomes an elaborate way of not writing. The world exists to be walked through by characters the reader cares about, and every hour spent on a region no one will visit is an hour not spent on the pages someone will actually read. Build toward the story, densely where it will go and lightly everywhere else, and you will have a world that feels whole without having wasted your life furnishing rooms the reader never enters.
In practice
Let the story lead the building, and develop the world most where the plot and characters will spend their time, sketching the rest just enough to imply it. Ask of any piece of worldbuilding what scene it will serve, and if the honest answer is none, either find it a job or move it to the notebook you keep for pleasure. Build outward from the characters' path rather than trying to complete the world before you begin. When you catch yourself deep in a genealogy no reader will meet, enjoy it as recreation but do not mistake it for the work, and get back to the pages that will actually be turned.
When it doesn't apply
Some writers genuinely need to over-build to write confidently, and if the surplus feeds the prose it is not waste but method. Series and shared worlds may justify development the current story does not use, banked for later. The caution is against worldbuilding that substitutes for storytelling, not against knowing more than you show.