I've been thinking about this lately. I'm a software developer, and until recently, I've never written thank-you notes. And most of my interviews have turned into job offers. It seems unlikely that most employers put much weight in this. I'm cordial in person, and express gratitude as interviews end, and this is likely enough. Now, a recruiter insisted that I send thank-you notes, and all nine people involved in my interview gave me their business card. So I sent nine thank-you emails, and it felt weird, and I have no idea what effect it had. Zero people replied to those, and the company eventually told my recruiter they "put hiring for that position on a temporary hold." Did the thank-you emails have any effect on that whatsoever? I really have no idea. However, if your position was client-facing, such as sales, consulting, support or project management, it would make some sense to me to see how comfortable someone was with writing that kind of follow-up message, and include that for consideration in the hiring process.