As much as possible. Those settings are there to do my work for me, so let them to my work for me.
I can always change stuff I don't like, and describe my part of the world however I want, but the detailed approach means that the rest of the map doesn't have to be white spaces with "here there be dragons" on it.
I find that it isn't so much of a problem with fellow players, since even if they read and know the stuff, you can always tell them that everything is subject to the DMs whims, and that their characters won't know most of that stuff, anyway. So if someone whose character never was to (insert name here) and starts complaining about the lack of (insert landmark here) or how (insert NPT here) isn't what he's supposed to be, you can always counter that his character can't know what he is, so his plans or outlooks won't change because of that. And you can also work together with those players who make an effort to give their characters a background that uses the stuff from the books: He gives you a first draft, you tell him what parts he'll have to change because they don't fit into the campaign, and while you're at it look whether his ideas aren't better than the stuff in the books.
It's great, everybody wins.