The TriggerCam was a pretty big step forward for those of us on the instructional side. There were always through optic camera options, but they were cost prohibitive or just clumsy.
The TriggerCam gives us the option to see things in real time (or later recorded) with wifi or hardwire connections. I can actually have a tablet and see what the student is seeing. It's a great tool for either self improvement or instructing others.
One notable example was someone I've known and coached off an on for quite a while. And at a certain point, there were at a plateau and we weren't able to help them a ton. Their fundamentals looked very good, or at least good enough to not be missing as much as they were. Once the TriggerCam was available we slapped it on. This particular shooter's problem was with their follow up shot corrections or lack thereof.
Many times they would not be confident in a correction (or at times just not see their impact), and send another round or two after almost like confirmation they were missing the way they thought they were missing. Now, you can figure this out via spotting and seeing the rounds impact in the same place. However, we've found (and verified with TriggerCam) that people will tell you they are correcting when they aren't correcting or not correcting enough.
Other times, this shooter would be on steel, but not centered. And instead of making correction to center, keep stacking them off to one side. Eventually they would make a bad trigger press or wind gusted and they would barely burn one off the edge which would have still be an impact had they corrected to center.
IMO, a TriggerCam is required equipment for anyone truly interested in being as good as they possibly can, or instructors/coaches to give their students and mentees that best value for their time.