Two versions of an old proverb: "God is in the details" and "The devil is in the details." I've heard both, and both bear applicability to the class I taught last night at Writers & Books.
We critique two stories each work, Clarion-style. Last night we had the start of a historical fantasy novel and a complete SF short story. One took place in nineteenth-century Europe and the other in high Earth orbit, but the same question arose for each: How much detail is too much? What made this complicated was that readers could not agree. Some liked all the details of Italy as seen on a Grand Tour; some advised, "Cut the travelogue and get back to the story." Some liked the details of the spaceship's propulsion drive; some said, "Too much techno-jargon." This naturally left the poor authors a mite confused.
My own take on this is that no matter you do, it will be wrong, in that you can't satisfy everybody. Leave out details of setting and mechanics and "the story feels thin," with White Room Syndrome (or White Starship Syndrome or White Continent Syndrome). Put in the details and "you slow down too much and sacrifice tension." Like everything else in writing, it's a trade-off. It's also a balancing act, but even if you find a good balance between atmosphere and action, some readers won't like it.
I don't know how these particular authors will revise their pieces. I'll find out when they send me their rewrites. Meanwhile, I struggle with the same question in the book I'm writing now. How much do you want to know about the furnishings of a seventeenth-century rustic kitchen? And if I tell you the family lights that kitchen with tallow candles rather than either wax candles or rushlights, will that help you place them on a socioeconomic scale? Do you know the difference? Should my text explain the difference to you? Who are you anyway, this unknown reader who may pick up this book two or three years from now, assuming it survives the perils of publishing?
All fiction writing is a message sent out in a bottle, with its recipients largely unknown. All we can do is print clearly and seal the bottle as tightly as we can.