Tore a deck yesterday and quartered both halves.
Today - tore two decks and quartered three of the halves and then just for giggles I put a single layer of Duct tape around a deck and completed my first successful duct tape deck tear!
I have been working on Adam's advice to be more upright and I have been focused on using the right amount of tension and positioning of my left hand. It seems to be working ;-)
I'll post a video when I can break out the actual camera and get a good film.
BTW - Adam didn't make a big deal of it when he did it but if I saw the video correctly he reached his goal of tearing TWO decks of Bicycles at once! Congrats Adam!