This is a drill used in an advanced pistol class by Larry Vickers. It's named after, and likely designed by, the legendary Rob Leatham. It's great for good shooters to do after some time away from the range or from a particular gun to reacquaint themselves with the trigger. It also works for more novice shooters who are in the process of putting all the fundamentals together.
Gear 18 rounds and an eight-inch circle as the target area. Paper dessert plates make a good substitute for printed targets.
Drill All three strings of fire in this drill should start with sights on target. Starting at four yards, with trigger finger straight and on the frame, fire six rounds in six seconds maximum. Move to eight yards. With the finger resting on the face of the trigger, fire six rounds in six seconds maximum. From 12 yards, with the finger on trigger against the "wall" with slack taken up, fire six rounds, six seconds maximum.
Goal Being able to "clean" this drill with perfect hits within the time limit confirms proper trigger control and, to some degree, recoil management. If you succeed at the first two distances but struggle at 12, analyze which of the fundamentals you need to address. Often it's just one. Moving to the in-between distance of 10 yards may help with that analysis.