I went on 12, got 13. 1 home program, 2 as a result of my 2 away rotations, and the rest were about 50/50 of places where I had ties, and places that I have no ties to. I also had a combination of expected interviews, ones I wasn't expecting, and also not getting a couple that I thought were for sure.
To echo what's already been said, I do agree that who you know and having letters that are recognizable by name goes a long way. I will also say that the vast majority of my 13 interviews were to places where I felt I could be a great fit personality wise--save maybe 2 of them. So that being said, the process worked pretty well for me and I'm now just sorting out the top of my list.
For what it's worth, I talked to an attending one time who said he was given a stack of applications to review, and to choose 10 to interview. After he had those 10, he just tossed the rest. After the applications have already made it through the first screen, they're probably all very similar and highly qualified. Sometimes it may just come down to where in someone's pile you land.
Over all, I met tons of awesome people on the trail, who I am sure are extremely well qualified for a spot. I think with each passing year the USMLE scores will creep up, the number of applicants will increase, and the quality of the applicants will remain just as high.
Good luck to everyone as we approach ranking deadlines and match day!