Tracking tempo and form

[JokerPSY]

For anybody training in the gym trying to build muscles: if you could visually see the tempo of rep while doing an exercise would that be helpful to your training? This is after you set the specific tempo that you want to do.
Also, if you could set a perfect rep according to your body so that you try to execute the best form as much as possible and after your set you could see from which rep or at what weight your form started shifting from the "perfect" rep would that be helpful?

For coaches out there and probably mostly for online coaches: would these metrics help you coach your clients?