When writing a story, it's necessary to keep everything straight so everything makes sense. The who, what, where, why, and how of things can get complicated when you have a sheet for every place and character. This is especially the case for speculative fiction as it contains many more possibilities than realistic fiction.
I was revising a scene in Journey To Chaos book 4 and it was the latest of the many occasions that I've been struck by the complexity of the fantasy genre. The supernatural nature of world provides far more in the way of world building and character ability and backstory then an equivalent story in a real life location. This is what Looming Shadow took so long to publish; there were many elements to keep in balance and account for.
When I took the whole work into consideration at once, and then the work in context of the series and the series in terms of the verse, there was a lot that I had to keep track of. It was a fascinating period of contemplation and reconciliation between plot elements, but it was also a long and, at times, tedious process. It was like hiking without a map; it's enjoyable until you get lost so I'm glad I had been keeping a map and adding to it as I went.
As in realistic fiction, you have to keep in mind the terrain and its nature, all the characters involved and their motivations, how the characters relate to each other, and the actions they would take in this specific situation, not as logic would dictate but as their individual characteristics would dictate. However, fantasy fiction has more elements. You could have different scales on the Super Weight, from badass normal to moderate magic to high magic to god like(and the level of divinity for each god-like character) in addition to skills that might be supernatural but not really "magic" as such. You might have to keep in mind the aspects of a non-human race in comparison to the human race, and how these affect other races. The area itself could have a supernatural qualification.
It's kind of like a Dungeons and Dragons campaign. "I have this character Bob, who has Y level of skill/strength/speed etc, S kind of equipment, a favored enemy of X, racial bonuses A and B, a skill set of G,H,T." Then you multiply this by the number of character in the scene. Character sheets are useful for summarizing them.
The scene I referred to involves demon mage mercenaries, chaotic elven anti-order warriors, and chaotic elven priestesses, invading a land blessed by the head deity of order and fighting elite orderly soldiers with the assistance of chaotic deities. There is a lot of information to keep track of that would not exist in realistic fiction and so I found myself re-reading my notes and previous books.
Now I'm revising this blog post and I realize it reads more like a prologue to a chapter than a standalone thing. I suppose that's why D&D books are so thick...