Every case is unique, I know some people who got their PR in few weeks even. there are lot of agencies CIC needs to work with including your country of origin law enforcement agencies and social services. their efficiency also matters in the case. I also heard from many source that case given to particular officer and case stick to that officer from start to end. if officer takes vacation or something case has to wait. Finally there is long queue and work flow, your file get officer's attention according to its order in queue. Even making frequent calls to CIC suppress your files position in the queue.