Movies get suffocating someone wrong, as well. It takes about five minutes to suffocate someone, yet the movies depict it lasting less than a minute. The most realistic for me of an attempted suffocation was in the Bond flick, On Her Majesty's Secret Service. In the end, Bond couldn't kill the henchman, so he had to resort to another means of dispatching him.
One thing I learned from watching crime documentaries is just how hard it is to kill someone. Though you may get that one stabbing or that one shooting that may down a human, it is really you being lucky.