Because interrogations are intended to coerce confessions, interrogators feel themselves justified in using their coercive means. Consistency regarding the technique is not important; inducing anxiety and fear is the point.
“The number one benefit of information technology is that it empowers people to do what they want to do. It lets people be creative. It lets people be productive. It lets people learn things they didn't think they could learn before, and so in a sense it is all about potential.”