I just feel, it is about getting to your application. Once they start working on it, there will be a quick response. Because all that history is supported by valid documentation. As long as you are in the queue, waiting for someone to pick it up, no matter how simple the application is, it will take long. A first come first serve based processing would have worked great but again it all comes down to the numbers i guess. Greater the number of applications, longer it is taking for them. They are seriously understaffed and i am not sure why they are not considering employing more people.
In my personal case, we are married, under 30. We have both studied and worked in the United States for 6 years. My wife works in USA right now and i work in India. Both have a lot of travel history to various countries. Travelled also while the application was under processing, but updated them with latest passport stamps via webform.
Also, i personally know people in a similar situation that got PPR under 3 months and also people that have a very simple application and waiting past 6 months. This is the worst part of it. We cant analyze to form a hypothesis and come to a conclusion out of it.