CIC has a reason not to respond to our request on the application status unless it goes beyond the listed processing time. I think the fact that we applicants keep calling CIC for an update may interrupt their work and slow down their processing pace. I believe that CIC is on the safe side with this official processing time as practically it takes much shorter. Perhaps they use the extreme cases to ensure applicants don't jump up and down complaining about the delay. So, I agree with you that there is nothing we can do but wait.
Your observation about smoother process with applications before 15 Dec as opposed to those before may not be supported by facts. There is no reason why this happens even though there might be a slight increase in the number of applications sent in right before the cut off. So don't you worry so much. I hope you would get at least your AOR (not PER) anytime soon.