Thanks for the advice, medstud.
I have a general question about letters. Personally, I would never send a letter of intent (expressing my you-are-my-one-and-only feelings about a school) until I was 200% certain I wanted to attend that school and that school only. On the other hand, I don't see why sending additional letters of interest/update letters could hurt.
How do you all feel about post-interview letters of INTEREST? You know, the letters that talk about personal updates but also include content expressing your continued interest in the school?
It seems like SDNers have strong feelings about letters of intent, as do I. But I'd love to hear your takes on letters of interest/update letters post interview.
Letters of interest are, in my opinion, rather anemic. It's sort of like when a medical school puts you on its "preferred alternate list." Your (unofficial) response is most likely "well, thanks school, now I feel all warm and fuzzy, but I still need to get into a medical school to become a doctor." I can't remember if admission has every told me specifically about letters of interest, so take this as general applying to med school advice. Letters of interest won't hurt you (unless you send them in before you are waitlisted) but probably won't help you much either.
The purpose of the letter intent is to inform the school "you can count on me to fill your last few spots" because at the end of the season medical schools want to make sure they matriculate the right number of people and in general try to avoid sending out acceptances after the school year begins. Think of it like this: every medical school has a ranked list fo all their interviewees in the order in which they wish to accept them. This ranked order is finalized after interviews are completed--they know who they want. A letter of intent is essentially a way to improve your ranking; it's more valuable to schools when they need it more, and not beforehand. A letter of interest basically tries to accomplish the "I really want to go here" effect of a LOI but fails to accomplish the "You can count on me to go here" effect of a LOI. If you did your job on interview day, schools should already know you really want to go there.
tl;dr: if a letter of interest makes YOU feel better, and you wait until after you are waitlisted, go ahead and send one. Just don't expect it to do all that much for you.
Again, this is based on my own personal experience and the feel I get from admissions faculty, whereas the "don't send LOIs before you are waitlisted" is verbatim.
P.S. Don't forget to send thank you emails/letters to your interviewers, you can restate your interest there, and do it expediently, you never know when the next admissions meeting is!