More about it ...
Disagree with applicantguide to a certain extent.
Yes, if you know someone who knows the PD then your chances of getting an interview is certainly high. If your connection took the job of actually recommending you to the PD, a task that requires a very high level of trust from the part of the connection to your potentials and skills.
However, if you are seen directly by the PD like doing an observership with him/her or presenting a seminar in front of him/her then your chances of getting that interview is even higher.
Of course, PDs are very busy and it can be very difficult to even have a short chat with them. But as I said, they are the ultimate goal, if you reach a bit more proximal goals then it's fine, but at the end of the day somebody should talk to the PD.
Another caveat here with the indirect PD connection, is that sometimes people tell you that they know the PD while in fact they are not or even worse sometimes they have conflicts with them or are "hated" by the PDs and a recommendation from that doctor may prove disastrous. So be very careful when you look up those connection. Faculty is usually (but not always) better than just "attending" or "external" physicians.
What applicantguide is perhaps pointing to, is the scenario when you practice undue stickiness to the PD despite his/her rejection. PDs and other professionals usually do not like "sticky" people. So the advice here is that show yourself just enough to be remembered in the match and do not press harder as it may be counterproductive.
In addition, some people may try to make an appointment directly with PD. Like for example they go to Hospital X and knock the door and present themselves to the PD directly. I myself know of several IMGs who have done this, but unfortunately very few of them succeeded. So it's always better that you are introduced via a trusted "someone" even if it was a nurse or a non-medical friend of the PD.
