As a writer of fantasy, this is an important question to ask.

The answer will vary from series to series and writer to writer.

The answer, I think, largely depends upon what your focus is.

Tolkien wanted to create a large, lasting mythology. As a result, his entire corpus is world building in a very real way. You have the Valar and Maiar, the first and second children of Iluvatar, and the development of Earth (Arda) through the first, second, and third ages.

I’m nowhere near that talented or that detailed.

In my case, I’m much more interested in character, character development, and my characters’ stories than in world building. I always say that I want my stories to explore what it means to be human. Thus, even in a fantasy setting and with a first installment with a ton of action, character is king for me.

That’s why book one is limited to the setting of one island nation. There’s a map for readers, and Herezoth has a history, of course. I reference the applicable period of ancient history that created a lasting distrust between those people born with magic and those without, as it’s necessary background information.

And that’s the key: NECESSARY BACKGROUND INFORMATION. I try to limit world building to what is necessary to understand the story, what is happening, and why certain cultural attitudes are what they are.

Each writer and story is different. Some fantasy stories, because of what they are, might require far world building. (I’d argue that’s the case with Tolkien, for sure).

In other cases, it’s fluff and adds absolutely nothing to the story.

I honestly don’t like world building and would much prefer to focus on character instead. But I want magic too! All the magic!