Just in the interest of clarity, I wasn't a Drill Sergeant. I was a company XO (previously known as Company Training Officer). After all the mess at Aberdeen, there was a big push to fill all the company-level XO slots as it was thought that having two officers in a company would make both officers more accountable.
One of the first things I did when I got there was to ask about the "stress card." I heard a different version of the story then, but even back then, no one had ever actually seen one -- but everyone "knew" someone who had.
It's kinda like the story about the guy who tries to kill himself by tying the floor buffer cord around his neck and throwing it off the 2nd floor balcony - only to find it has a 30 foot cord. After the buffer breaks, the kid ends up paying a statement of charges for the buffer.
Later i heard the same guy tried to tie the cord around his neck and jumped out the window but broke his legs on the way down!
I would imagine if these stress cards were actually used it was limited to one or two companies to see how it worked. If true, i would think with all the negative rumours flying around TRADOC would quickly discontinue the idea.