I have been searching for a method of outlining that I learned at a con, and I ran into this:
http://www.streetdirectory.com/travel_guide/15730/writing/are_you_the_next_jk_ro...

JK Rowling spent 5 years building her world before she ever started writing. That's amazing! How many of us have put that much thought into the pre-writing phase? Not that you can't fix it later with editing and such , but it really explains a lot.

This quote is also golden: "Not that you have to listen to what the editor says. In the end it is your name on the spine of that novel and you are entirely answerable for its contents. Having said that, a good and subtle editor can lift your novel to heights that you may not be able to achieve on your own."

which ties it right back into the spoiler discussion.