I would like to think that during TOS' time, and even ENT, that all interior spaces are continuously monitored by cameras and microphones. "Court Martial" demonstrates that there are microphones literally everywhere. And this system is monitored by the ship's computer system, not by humans. Using voiceprint and facial recognition tech of today. The computer would maintain a lock on every individual's location and identity 24/7 with or without a combadge. The computer would be able to learn and know the schedule and routine of everyone on board. Which would be usefull in allocating resources, especially the operation of the turbolift system. Ensuring that nobody has to wait for one. (See other thread on turbolifts)
I don't think that this is really touched on because it smacks of invasion of privacy of the crew. Plus it would wreck the plot of a large portion of episodes.
Lt Torres showed us that every viewscreen has a camera that's turned on. Even in the bathroom.