It's working by extended Battlegroups (ie : multiple battlegroups pulled together), not by server.
And honestly i find it hard to see how the CtA could even remotely be responsible for longer queues....
It can only have 2 effects :
- none, because it doesn't put more people into tanking/healing
- reduction of queues because more people queue.
You need to compare the Release Cata HC queues with what they were before, Zandalari ones are DUBBED to be longer to the higher gear and ability requirement AND the fact that they take longer (it's not unusual to be the 1h15 or more in those instances sadly, and it's not often you'll go under 45 mins, while all the old ones maybe excluding Deadmines are done on average under 40 mins, some in 20).