I did some additional reading up on this late last night...

It is the clips in conjunction with the double drywall/Green Glue, plus most people attach the clips at every stud on walls (16") when the recommended spacing is 48" meaning that they have 2 additional connection points for every 2 that they are supposed to have, and since the point is to decouple with the clips/channel, and then dampen with the extra mass, if you are missing one, you aren't getting a lot of benefit. For me, I have my walls decoupled already with staggered studs, but my ceiling will still be coupled, and adding mass of the DD+GG will help, but not nearly as much as if I do that (increase mass) and decouple (clips/channel)...

Plus if all surfaces aren't "treated", you can get sound flanking, meaning that if the walls are done, but the ceiling/floor isn't, then sound can transmit to/from the ceiling/floor via the walls, or vice versa and you are screwed.

The analogy that kept coming up in the research I was doing was the old "aquarium" one. Sound will escape like water from a leaking aquarium if you don't have all surfaced treated. I'm not sure how fish get food/oxygen in such an aquarium, but that was the analogy used a lot.

Farewell - June 4, 2020