They have the time left for the show that they accepted. I know I would have much rather had 10 episodes for this and next season. It's pretty much the most popular show there has ever been. If they can't make money making more shows then they are dump as ****. There is no excuses. They want less shows, they need to keep quality for the number of shows they decided on. They are delivering the action, but action is not the backbone of this series. The storytelling has suffered.
Their excuse is that they had to wait until winter to start shooting this season.