One of the things most difficult to balance when writing a book can be how much uniqueness to invent for the world it is set in. It’s easy for some stories, such as historical fiction. For Science Fiction or Fantasy, it can become a huge part of the creative process. Among authors this is referred to as world building and magic systems.
I don’t know if world building is the best name for the process. It’s really just imagining and designing the setting of the story. The most famous example of someone who did a lot of world building is J. R. R. Tolkien. He wrote genealogies, drew maps, and created whole languages for Middle Earth. Few will doubt the depth of the setting he created, especially since it then grew to be an entire literary genre. For most authors, his level of creation is counterproductive. It takes a lot of time and thought which might otherwise be dedicated to actual writing. Certainly his stories are richer for the effort, though.
Currently, one key aspect of world building any fantasy story is the design of the magic system. In some cases, it’s become so formulaic that it feels unoriginal. Many authors base their system on something common or mundane like colors, blood, or archaic elements. There are rules, not unlike a game, which govern the use of magic in those stories. Although sometimes the methods of usage can overtake the story, clouding other more important parts such as character and plot.
How much is too much? How much is too little?
In questions of balance, the correct answer always lies somewhere in the middle. I once spent ten years building a world. To be clear, we only wanted to design the setting, not actually write books or anything. Halfway through we decided to start writing books set in that world. We discovered something surprising– it’s harder to write in an over-developed world. We had so many ideas, that the first books turned out to just be an unending flow of concepts to the point where characters and plot were quite far down on the priority list.
Part of the problem was probably our own lack of experience and still learning to write books. Eventually, we learned to write about characters and leave out any insignificant world details. My partner in this crazy endeavor, R. A. Baxter, just released his first book set in that world: Where Nightmares Ride. I highly recommend it. You can see the world we spent so much effort on.
Too little development can be just as bad. I recently read a mystery set in the future, but the science fiction elements were so sparse as to not even be relevant. There wasn’t any great technology or advancement. It felt like a modern day detective story with a few gadgets thrown in. Such a situation leaves a story unfulfilling and rife with plot holes. I couldn’t help but wonder why there weren’t any advances in forensics technology in the supposed forty years between now and when it was said to take place. If nothing else, too little world building will just disappoint fans of the genre being ignored.
The exact balance is art, not science. I recommend enough for flavor, but not so much it overwhelms the story.