I haven't had an opportunity to watch it yet, however I do personally know some of the sound crew and have heard it's a very great-sounding show - and I imagine that from seeing hat's it's aesthetic is like, it is a highly-demanding show as far as sound.
The earlier seasons were helmed by Peter Brown over at Soundelux, which they recently garnered a Golden Reel for, and more recently helmed by Paula Fairfield and Tim Kimmel at Todd-AO.
There was a great article I read somewhere that shed some light into the post process that Fairfield and Kimmel go through on the show, down to creating walla tracks using group ADR recorded with specific linguistic dialects to match the show. And what I was very surprised by was that they had the whole season delivered up front, so they could treat the post process almost like a really long feature film (but essentially in episodes instead of reels).
I wouldn't say this is unprecedented or unheard of, but it does seem abnormal for primetime TV and it probably does owe to why the sound design is so cohesive and well-thought out and always a top contender. They've had the wonderful opportunity to embrace the entire season at hand in the way you might approach a feature. Primetime TV usually has 1 week of sound editorial per 1 hr episode - even on the high-action shows, so sadly we don't often have the time we want to really do something special each and every time like we would on a feature. We sort of have to pick our moments and work strategically. It's not to say we do less or a worse job or anything like that. It's simply to state that this is just not the norm. I'll have to check it out sometime.