adventure filler content
Not sure what you're referring to there, but okay - Robert Jordan usually has more than 1 character's POV per chapter.
Robert Jordan managed to do 10 books before he died.
Since I have never even heard of Anne perns series I can likely guess it's not nearly as epic.
Please, I'd never heard of ASOIAF until they started making a TV series about it, and at that point I'd been reading fantasy and science fiction for about 17 years.
Look at Steven Erikson's Malazan book of the Fallen - if you think ASOIAF is complex, those books will shatter your mind. He's already finished that series, and has put out several other works as well.
My point stands - Martin is taking much longer than you'd expected. He's probably distracted or has hit a block or something.