I would agree if it was someone who was a preceptor that you were shadowing. Sending a thank you to someone who has to grade you seems just wierd to me.
My biochem instructor took time out of her day to teach me in first year too and i never sent her a thank you.
Personally, i was raised to give a simple verbal thank you on my last day.
Valid point about if the attending was just giving the grade while residents actually did the teaching that month. In that case, or if it's a really big service, I'll usually give one card to the residents and one to the attending, letting him know how much I appreciate the opportunity to have worked with his team and how welcoming they were to me. If I'm at a private doctor's office, I include the staff in the card because they do a lot over the month to help the student figure out where to be. I'm very careful in my wording to not say anything about my grade or about wanting to interview there...I make it as clear as I can that I'm simply appreciative of their time. Again, if someone is going to get all out of sorts about a card, then I'm not going to worry about it.
I would do this (and have) for an internship or volunteer position of any kind, some of which were graded. I've done this after job interviews and when I was leaving jobs, and I've never had anything bad happen because of it. I used to teach and would receive thank you cards/gifts from students at the end of the semester before grades came out. I was appreciative, but it didn't change their grade - it was what it was.
And yes, I have sent thank you cards and holiday cards (with caution, based on what I know of a individual's view of holidays) to professors. Not as often, but I think one-on-one time in a 4-8 week rotation is a different situation than a professor giving a lecture to a class of 180.
Please don't think I'm criticizing others who don't write notes, as it's a matter of personal taste. I'm just saying it's not some horrible crime to do so if you choose. Maybe it's a generational thing (I'm a bit older than the average med student) or a cultural thing (I'm from the deep south). Maybe I just had really formal parents and grandparents...who knows?
Ethics? Maybe if I went into it hoping for something out of it. I'm not. I'm just genuinely thankful that people have given up their time to teach me, knowing that med students truly do (often) create more work than they help alleviate.
I hope this post explains my thought process better. I think sometimes we medical folks get caught up in the idea that you can only do something one way, and if you don't then
Oh my word what is WRONG with you??? And that's not really the case. It's a business like any other, and as long as you don't tap dance naked down the main hallway on your way out the door, you're probably fine. Besides, it would be pretty boring if we all did things exactly the same, right? (Inner nerd alert) Infinite Diversity in Infinite Combinations!!