What it boils down to for me is that here's a guy who says originally "I have this planned out to nine movies." then years later vehmently denies he ever made that statement and that it was always supposed to be 6 and now we find out that it was essentially made up as we went along kind of structure.
The process of writing a story is a hefty one. Maybe before he started writing, he thought, "I bet I can make fifty movies outta this!" Then when he started into things a bit, he probably thought, "Maybe it should just be twelve. Or ten. Err... nine's a nice number." Then, when he was halfway done, he thought, "If I make nine films, it'll stretch too much. Better just make it six." Then he's going, he's three-quarters of the way through, and he's thinking, "Y'know, I should just focus on the first trilogy right now. I'll make others if I have a chance."
So he finishes the first script in his trilogy and presents it to Fox, and they say, "Eh, we'll give you a million bucks." And Georgie doesn't think he'll ever have a chance to make all three of his movies, so he adapts it to make just one.
In short, don't think that a writer can see into the future. And never, NEVER think that writing is an easy task. Try it sometime.