But does he have a talent for finishing stories, lol. Maybe the series is dragging on so long because he's afraid of writing an ending / doesn't know what to do with it.
Or maybe it's hard to create a world this dense? He's finished plenty of books in the last forty years so I'm not sure why you think he can't finish stories.
I'm a little late to this but Young Griff not being in the show pretty much means that he's not a real Targaryen right? Or that his character is generally unimportant to the end game one way or another.
Or it means the stories have diverged.