Would you be able to keep an accurate count if you were in an incident that involved a reload in a stressful situation?
What if you carry guns with different capacity? What if it is a stovepipe, or type 3 malfunction? The trigger feel will tell you something is up (also the gun not going ‘bang’!).
One of the best classes I went to was taught by a 1911 fan, but all guns were allowed. We partnered up, and he would tell us how many rounds and how many mags for the drills. And your evil partner loaded your mags, so you never knew what would happen, get that gun running and hit the targets.
It was a great learning experience, because the instructor only told number of mags and number of rounds to load. After that was done he showed the shooting drill, so everyone got tons of reloads to practice.
I am not a shooting expert, but have done drills random or with counting. I can run a drill faster if I count, and load for it, but is that really the way to train for what we don’t know?