[CliffFletcher]

Martin has said all that he's not a writer who plans. He's a gardener, not an architect (in his own words). So yes, he makes it up as he goes along.

I'm not sure the popularity of his characters had anything to do with his change in plans. He was a fairly obscure writer for the first couple books, and wasn't active on the internet. And if you read the original outline he submitted to his publisher when he signed the deal for the book series, it was already discarded by halfway through Game of Thrones. He could hardly have known how popular the characters were before he had even published the first book.

The intended multi-year gap between books became an issue because he found he had to start the second book with pages and pages of awkward exposition to get the reader up to speed with what happened to dozens of characters over the last few years. That sort of structure is possible if you're a very disciplined writer who plots everything out in advance. Martin, by his own admissions, isn't.

So yes, he bit off more than he could chew. Not because of cynical reasons of popularity or money. He's just an undisciplined writer who tried to write an epic whose scope was beyond his grasp. Still, the first three books are excellent pieces of fiction.