It has no practical application in the real world.
BG US
Gun Gun
Knife Gun
Club Gun
Physical Chem, Taz, Baton, H2H, Gun, (whatever it takes to win)
Threat Verbal, Chem, Taz, Baton, Knee knockers/rubber, H2H
Nobody trains to shoot one round and wait for the full reaction. We train to shoot until YOU PRECIEVE the BG is no longer a threat. I hate the term follow up shot(s). It infers you are firing a distinctly different shot(s) from the preceding shot(s). As such, you stopped shooting then resumed shooting; calling for a conscious decision to do so. Don't leave that void for IA, DA or Lawyers to screw you with. You fire a "SERIES" of shots. You may need to fire an additional series of shots. Lawyers will push follow up shots to equate to Coup de Grace (killing blow).
What do you think would happen to you if you intended to use the "Device" for less then lethal force but fired three times as you trained to do for years. We have enough problems with Officers mistakenly using their weapon instead of their tazer. Too many Officers don't have good firearm skills and this could eliminate their first and maybe only shot if installed.
It will probably be mandatory in San Fran, NYC and Balt. Lol