I shoot a variation of it frequently.
For all of the legal ramifications it’s best to not train for head shots in this manner.
If you want to work on rapid transitions from HCM to a point target take a can of orange paint to the range with you or some target stickers.
The more precise your target the slower you’re going to shoot to hit it with any accuracy.
You can build both speed and accuracy practicing on small point targets.
The Standard USCCA Target with the colored and numbered circles works great and I think is a better drill than this one.
You start with “Extend, Touch, Press” at a 4" circle and finding your max range to get consistent hits without time pressure.
Then cut the distance by half and have someone then call colors, locations, or numbered circles out and from the High Ready engage them mixing up the number of shots and number of targets engaged in each string.
You identify the called target before extending.
This will really build those neural pathways/muscle memory and greatly improve your eye hand coordination.
You will find a maximum speed for any given range.
I’ll also tell you to always start and finish at a range you can succeed at.
It’s never good to leave a practice session frustrated or feeling like you failed.