When people talk about worldbuilding, they sometimes use setting and world as though they mean the same thing. They are related, but they aren't interchangeable. A setting is where a story takes place. A world is the larger system that makes that setting what it is.

There is no magic number of pages. There is no required number of countries, historical events, religions, cultures, or magical systems. There is no minimum amount of worldbuilding you must complete before your world is “properly developed,” and there is no rule saying you've gone too far because you've created more worldbuilding than will ever appear in your story.

There is nothing wrong with building a deeply complex world. In fact, readers often love deeply complex worlds. The goal isn't to avoid complexity. The goal is to build complexity in a way that readers can understand, remember, connect, and become fascinated by. Your world can be as complicated as an encyclopedia. Your readers just shouldn't have to learn the entire encyclopedia at once.

Worldbuilding is an exercise in systems thinking. Every decision you make influences dozens of others, whether you intend it to or not.

Will magic behave like chemistry, with clearly defined rules, limitations, and predictable outcomes? Or will it remain mysterious, unknowable, and almost divine? Will readers understand exactly how your floating islands remain suspended in the sky, or will they simply accept them as part of the world's wonder? These questions all lead back to one of the most fundamental concepts in fantasy writing: hard worldbuilding versus soft worldbuilding.