Dear Shortsighted:
Really? You have better ways of creating fear than torture? You can motivate people to success without exhibiting the weeping wrecks of failures even a tiny little bit? Without the threat of pain from somewhere hanging over them, maybe not from you, but somewhere?
I'd tell you not to despair of your own incredible incompetence at torture, when maybe all you need is more practice. But before then, I want you to look around at the society around you, and realize how many of its institutions are born in pain, shaped to horror, and require fear in order to function. You may not have gotten better work the next day out of the particular worker you tortured; but if not for your doing that much, the other workers would slack off, and worse, disrespect you.
The most important thing you get from hurting others, is living in a correctly functioning society where people fear getting hurt, and where they fear getting hurt by you. In claiming that 'torture doesn't work' you're just being shortsighted in your understanding of how often people inflict hurt on one another, and how the fear of it underpins all of the social order around you. You threaten the people around you with a hundred little tortures every day, and those threats work. If you can learn to see that, you'll maybe start to understand how to wield larger tortures the same way.