I was interviewing students for this volunteering position and I remember how the volunteer coordinators were talking about previous days candidates
"hey, a few of them sent out emails with a thank you... that was nice of them!"
so it is a matter of a formality... but like anatty said, if you can write it right after -- along with something that you talked about at the interview, i bet that would make a lasting impression.
whenever i write out thank u letters i always feel like i am b.s-ing... but whenever i get a thank u letter from someone, i smile. i never think, oh they are sucking up to me.
so... 🙂 do it! =D
**this reminds me... i need to write thank you letters to my recommenders....