People that understand the theory behind shortstacking and have a good enough feel for hand ranges to do it well don't play shortstacked. Not many anyways. So many of these concepts are independent of stack sizes. What changes is how they're applied. Sitting with 40BBs isn't going to change much other than how much you can potentially win/lose if you aren't already able to beat a game playing with 100+BBs.

At midstakes and below shortstacking is next to worthless. Good luck assigning hand ranges when so many of your opponents are playing erractically and often times just according to whim. Often times you're just minimizing the extent of the mistakes they make and giving them easier decisions.