It's easy, when doing the pull cut, to have the knife at too much of an angle, almost horizontal instead of straight up and down.
This causes your wrist to collapse as you pull towards yourself, which saps most of the power from the cut because now you're using your wrist muscles instead of your back and shoulder.
It also exacerbates carpal tunnel syndrome by pinching the nerve connection that goes through your wrist.
You've been warned. Keep your wrist straight at all times.
My blog has evolved into a series of short essays on the nature of entrepreneurship, craftsmanship, and their overlap. If either of these topics is something you think about, you will probably like this.