James at 2009-11-28 14:25:30:
Most story structures just turn out to be slight variants of the main three act one (as detailed in Syd Field's 'Screenplay'). Every story has to have a beginning, middle and end, and each of these is going to breakdown into a number of shorter sequences.
As for established paradigm vs. organic - I find the three act structure (with it's various plot points) extremely useful when I'm outlining and writing the first few drafts. But then I think you have to put it out of your mind in the latter stages and go more with what feels right for the specific story you're writing.