Yeah, one of the big differences between us is that for me the setting is important mainly as a place where things happen, and they happen in the game to and around the PCs; the characters and the events matter more to me than the setting does. I'm not trying to model anything, at least not the way you'd use the word.
So, for instance, I know that in the campaign I'm running where the PCs are 6th-level, the things they're interacting with are pointing them in the direction of things connected to the deep history of the setting (using places like the Hopewell Culture sites in Ohio as inspiration for locations in-setting), but I don't yet know where those places will be, or what exactly the PCs will be able to accomplish there (presuming, of course, that the PCs maintain interest in those places and survive getting to them--honestly not completely guaranteed).