When I was first trained to shoot in LE academy we shot center mass only (on bullseye targets). That was 32 years ago, we also used revolvers. A few years later we went to a silouette target and center mass only. I became a range officer and learned more about training others. I saw shooters that could make head shots under stress at 50 yards and others that spread 5 out of 6 rounds all over a silouette target (who knows where the 6th round went)
In the early 90's our agency went to The 4043 S&W DA only pistol allowing us 12 rounds without a reload and 2 more mags instantly available. We concentrated on center mass hits and with body armor more readily available we taught 2 center mass then quick evaluation, 2 head shots/groin shots.
We were taught to shoot only to protect ourselves and others and to shoot only when deadly force was required. No shots to hands or legs were taught but I still saw a few shooters that threw shots into those areas. I know of another agency that was taught the ZIPPER method. Start shooting at the groin (or lower) and as the recoil of the gun causes the muzzle to rise keep shooting higher stopping at the head (or threat ended).