That's a good way to think about it, though I haven't done much as a dungeon or game master. Along the same lines I like thinking about it the way Inception talks about how to architect dreams.
But the question isn't so much how much do I put in the story. Though I think that those that do more architecting tend to have more troubles with info dumping than those that "discover" or "grow" their story. The question is more about what to do outside of the story in terms of design and brainstorming, so that when you are putting the story together you don't end up with missing or awkward pieces, week (or sagging story line), characters that end up doing too much (taking over the story) or too little, ... [the list goes on with potential pit falls to story telling]. And while each beta reader, friend, or editor that looks at the story might pick up on some of these and help alleviate the problems they find, they might not know exactly what or where the problem is, or inadvertently lead you into new pitfalls.
Maybe it's partly a question of writing tools. How do you outline, or keep track of all of the ideas, characters, threads, ...? How do you make sure you have a solid, exciting story? How do you make sure your cool, amazing ideas get put together in a way that doesn't fall apart?
Have a firm idea of the events that need to happen and then the next thing is the order in which they need to happen. These are the 'milestones' you need to hit along the way. Next are your characters and those cool little twists and things that 'could' be optional but that you really want to put in.
After you've got those down with the first set 'the milestones' almost set in stone and the second set the 'characters and twists' more malleable to allow for story telling the only real thing left to do is write it.
Its a horrible thing to hear but the first book you write will suck (thus sayeth 90%+ of published authors), however after its written then you have 'bones' of a story. Anyone can edit the bones (now they may not be very good at it) but very few people can pump out a 300-400 page book that is in dire need of editing. Once you've got your ugly Dr. Frankenstiens skeleton then its time to finish putting the meat on it!
As for everything hanging together and being consistent... everyone's got a different way of doing it. I know people (published authors) who write 10k plot outlines. I know people (published authors) where just about everything is in their head and at the end of a book they've written a separate file of about 2k worth of words strictly for keeping the names of your characters, et- important people, places and things.
Its like with game mastering or taking notes in class. Books are like classes. Some of them require you to take notes early and often, others you have to slavishly write down everything you hear from teh teacher before taking the test. Others you can wing it. However in any group of students. Some will take notes even if its not strictly needed and others will do their darndest to take as few notes as they can possibly get away with. A large part of this is memory and personality.
Some Game Masters 'need' a gaming module, and not the module, it has to be right in front of them before they can run an adventure. Other guys, read the module once and reference it occasionally for important events. And then there are the Dungeon Masters who run everything in their heads and only write down important bad guys and then only their vital statistics.
The answer to your question is pretty much that there is no hard and fast answer to your question. Which is an answer in itself. You don't 'have' to slavishly plot out everything in advance, unless 'you' have to do such a thing to be able to write. Also you 'could' write nothing down in advance or as you're going. But most people try to find a happy medium.
I will say for my first book the brother and added 10%+ of new material, and must have rewritten three times that. For my second book, we added entire sub plots involving two pivitol secondary characters who only got a couple of high stakes mentions in the main line, the sub-plots were added 'after' the book was already written, so that none of the 'coolness' of the story was missing or left out.
When I have logical disconnects of time line inconsistencies that I missed, we have to take a hard look and fix it after the book is written. I keep a running file of things I need to remember as I go along, this file is separate from my book. I've even written a couple hundred word plot outline for my 5th book. (the first book I've ever done this with)
Asking how you learn how to do these things? The answer is like asking how do I learn how to ride a bike? First you watch and are told things like hold the handle bars straight and pedal. Then just have to get up on the bike and wobble around before crashing and burning. After a few tries you'll get the hang of it.
Sorry for rambling, its getting late.
The Deposed King