It's to avoid "Arya spending four episodes on a boat."
Oh, one thing since a few people have asked me. The timelines of the various story threads don't necessarily match up all the time.
— Bryan Cogman (@b_cogman) June 27, 2016
This is to avoid things like, say, Arya spending four episodes on a boat.
— Bryan Cogman (@b_cogman) June 27, 2016
Oh, and in case people think I'm annoyed at the question, I'm not. I tied myself in knots season 1 trying to make it all line up. 1/2
— Bryan Cogman (@b_cogman) June 27, 2016
We realized right quick doing so would kill momentum. So there you go. 2/2
— Bryan Cogman (@b_cogman) June 27, 2016