That isn't the case with the control systems in the OP.

From the OP

If this was only about cruise controls and room thermostats, it would just be a minor conundrum. But it is also about people, and all living organisms.

My point was that features of the thermostat that the OP attempted to generalize to control systems used by people do not actually generalize. A thermostat is a simple system to solve a simple problem (though it still takes some evidence, that a given device cools or heats a room). A more complex problem requires a more complex solution, and more evidence to calibrate.

All that matters is that the system responds in a way that (1) approaches the desired state, and (2) won't overshoot---i.e., won't reach the desired state so quickly that the system can't turn off the response in time. These seem to be what were missing with your sailing students.

While technically true at a certain level of abstraction, that is just not helpful. The reason why the students do not approach the desired state, or overshoot, is important. If I just told them "approach the desired course, but don't overshoot", it would not help. They already know they want to do that, but not how to do that. I need to tell them more precisely how to use the tiller to do that. I tell them, "pull the tiller towards you, a little more ... now back in the center", and get them to observe the effect this has on the boat. It is after going through this exercise a few times that they are able to implement the control system themselves, and process higher level instructions.