Having been a bit of an "anorak" on these stats and someone who is currently actively involved in the processing of submitted papers, my feeling is that there is a little bit of luck involved too as to how quickly a particular application is processed. I get the impression it can be quite random.
I know someone for whom it took a day. And there has been an example on the forum where this has happened also. For others it has taken a lot longer. For us it took 2 weeks which was slower than most at that time, but quicker than most at other times.