a friend who is in my local writers' group. He had a story that he'd started, but got bogged down and quit. Since he'd read part of it in group, I knew where he was, but didn't know where he was going.
So, I started asking questions about his vampire story: where did the central McGuffin of the story came from and how did it work. Dave didn't know, so I started making stuff up and asking Dave if my handwavium was consistent with his vision for the story.
I got wild and crazy and started making connections, of the McGuffin to the Holy Grail, and then to Prester John who guards it in Shangri La. And if you have some two-thousand-year-old warrior dude, he'll have to have a foil that a contemporary reader would relate to this could be a brash apprentice I termed "Star Wars" John.
This put several sticks of dynamite under the creative logjam.
And that's the lesson for today. Ockham's Razor states that among competing hypotheses, the hypothesis with the fewest assumptions should be selected. Extending this notion to design, given multiple designs for the same device, favor the one with the fewest moving parts.
Some of it should never see the light of day and should forever remain "scaffolding." Some has to go into the narrative to make the current scene make sense. And some will make for a delightful springboard to another story.
Nevertheless, all of it is tangential to this story you are telling now. If your story must be Teflon, you can't disclose any of it. And if your story can be Velcro, you can disclose lots of it. You need to maintain a balance between these opposites.
Don't be afraid of feeling some tension while you decide this. The tension makes things interesting.