re: Writing Thank You after Interview with Multiple Interviewers

Mostly it depends on how long the hiring company's interview cycle lasts.

Personally, I conduct interviews for one of the top 20 IT services firms and we start a typical day right after lunch. All the interviewers have submitted their recommendations by 5pm. A handwritten note is obviously a waste of time since the hire/nohire decision is already in the bag.

But there are other situations where the hiring cycle is longer. If you're looking for a spot with a small firm it makes much more sense, but for a big firm with a well-established process the decision was probably made before you got home.