Actually, the six foot leash becomes a bit shorter since I wrap it around my leg. Also, I use a short piece of soft nylon anchor rope because they will chew and ruin an expensive leash. And yes, these sessions definitely help with biting issues. Too many times (early on) the pup is free to run when he bites and corrections are ill timed. Being loose allows issues to develop. Tethering sessions prevent the “mongoose dance”.
First, tethering in the living room, you just put him on a 6' leash and that is his distance? I haven't tried that with my 8 week old, are you saying that this helps with the biting?
The "quiet room" is actually the pool room. It is warm and pretty much sound proof. The pup sleeps there at night and I get up (alarm clock) and take the pup out in gradually lengthened intervals. Afterward, I have no idea how long it takes for a pup to quiet down and everyone in the house sleeps well. ;)
Also, you mention sleeping in the quiet room in his crate, at this point do you have him sleep through the night without airing? Mine sleeps in the crate but usually once per night I have to get up and let him outside, then right back in crate which usually takes a while for him to quiet back down.