again - same person who first said that interviewers told from top firms told us they do not want thank yous. according to them, here is why:
after they interview you, they give you a mark. they then report that to the hiring committee after the interviews are done that night. your email will either arrive prior to 5:20 when they are still interviewing (which they laugh at said they won't read), it will arrive after they've already graded your interview prior to reporting to the hiring committee, or lastly, your email will arrive after they've already reported their decision.
so in the second scenario, is it only likely to be of any significance. and these interviewers, all who interviewed here, all for top firms, said the only thing it could do is hurt the interviewer.
they get hundreds of emails a day...they don't want anymore.