Why "corkscrew" your punch?
In my view the reason so many martial arts utilise the standard "corkscrew punch" (eg. karate, taekwondo, many shaolin schools, etc.) has little to do with a conscious effort at enhancement of power/stability, or because of fashion or aesthics. It is simply a function of our biomechanical design. Consider a very short, close range punch into the ribs - with an uppercut type action. Your palm will naturally face upward. Think of a handshake where you are middle distance (ie. your elbow is not fully extended). Your palm is side on and you have what is known as "vertical fist" punch. Now think of an extended "raise your arms in front" (as a doctor or physiotherapist might ask you to do) - or even a pointing action - ie. where your elbow is fully extended. The most natural position is palm down. Hence when you have a fully extended punch it will naturally end up with the full corkscrew. The standard "karate-type" punch covers all three of the above &