HR practices

what we been learning in HR was just plain common sense or deeper than that? What was new in dressing up for interveiw which was not practices when getting ready for school or family get together. How as sitting in an interview chair different than sitting in a disciplined class room. What manner of speech was new for the interviewee which he was not guarded against before so many times. Does the learning fade away with time? Does learning can so easily be hampered by other hostile environment that relearning becomes a continous affair.