This week's drill is not a specific drill so much as a modification of the drills you already shoot.
At a recent Massad Ayoob class, we were challenged to shoot from a stance that was not our preferred stance. The reasoning for it is that you should evaluate all modern stances on their own merit, side by side. So when the qualification came, the drill was performed from the isosolese, Chapman and Weaver stances, with a reload between each position.
This forces you to position your body in an unfamiliar orientation, and has a side benefit of familiarizing your body with awkward muscle tension. The body stabilizes itself through muscle tension differently in each position and actually feels different.
Finally, if you set up 3 targets at 5 yards away, 5 yards apart, you will naturally shift from a Chapman position on the leftmost target, to an isosoles position on the center, to a Weaver-esque position on the right. When we naturally turret out upper torso, the arm tension and position changes through these stances.
Work out how to use these stances and positions to your advantage and don't be afraid to try a new one!