This whole game is... ugh. I get why we have a match, but I really wish it were a more honest and transparent process. Some PDs send interview feedback quickly. Some hardly respond to e-mails. Sometimes a great program will write an e-mail making you think you're the best thing to come along since haldol and some will write something like we appreciate that you like us. Very similar to clinical comments. "DWD has very good clinical skills for their level of training." If someone said this about me in standard american english, I'd be thrilled! In med school english, it means that I'm pretty far below average bordering on bad. The problem is, we never really know which language any particular person is speaking (except for deans and course directors), and we rarely have the official decoder.
On this end, how many candidates do programs actively try to woo and spend extra time, effort and money on, or at least e-mails that say something like you would be a really great fit for our program or everyone who interviewed you said wonderful things. Does this mean that I have a spot for sure, almost certainly, I'll probably match here or I have a fighting chance? Are blandly positive e-mails like saying my clinical skills are good (aka you probably won't match here)? What about hearing nothing (unless a program explicitly states that they won't communicate post interview)?
The experience that this whole process most resembles in my mind is online dating in a major metropolitan area... we swipe right, you swipe right, sometime we have to message you, we drive long distances to see you, some of you might takes us out to dinner, if we're really lucky we get a hotel, sometimes you write us back the next week and ask if we want to watch netflix and chill... but all the while we're flirting with many others and so are you, and rarely does either side actually end up with their true #1, but often in the end it works out for the most part.
I've sent many letters than said, "I really really really really really like you, and I want you, do you want me too?" and it's pretty true, I'd be very happy there. The responses have ranged from "OMG <3" to "I think that you're really nice, but..." I also sent one where the like almost sounded like love, and will probably be ranking them #1. I just couldn't help myself: they said that they also like cooking with kale, hiking, were obsessed with Serial and had a really cute bathing suit pic in their profile *wink*!
Just as many of the love letters from applicants probably go out to the reach program that interviewed them, I think that the opposite is probably true as well. Those who stand out and a top middle place interviews them probably get love letters from slots 4-10 on their list... I just really wish that I could have a better decoder right now (feedback has been all over the place), because I'm spending a lot of time and effort flirting and being flirted with, when all I really want is to get some commitment... someone's gotta just put a ring on it.
So to answer you: No, I'm not planning to send a real "you're my #1," although I'd love to receive one. Programs generally have less to lose, and I want to reserve the right to be hit on until I get a ring from my #1. More information from programs to me can't hurt. With that said... much has been written about noise in applicants on this board. The great many applicants who, for better or worse, can't really be distinguished because they have OK boards, OK clinical grades and come from OK schools. They are average for the place that they match into, and they interview just fine. Perhaps it does make sense that a "you're my real #1 because of X, Y and Z" would help? PDs want happy residents and if they really can't think of a good reason why person B should be ranked over you, this could help... beating the coin flip? Not hearing from programs does kind of make me like them a little less... but only a little.