Frankly, there is no way the Watch can check “thoroughness of the washing.” No way. It’s called the Apple Watch not the Magic Watch. It only checks that you continue to wash your hands. It serves no purpose except being able to scold you if it thinks you’re not washing your hands. When I wash hands it often stops counting in the middle. So, I simply give up following it. By being so paternalistic it becomes less effective.
I think some Apple engineers overthought the problem. They should simply have made a 20s time started by detecting hand washing. Instead they made a Rube Goldberg machine that does not really solve the problem.
Yes, way. Since the Watch has an accelerometer and microphone it's indeed able to measure
indications of thorough washing - continuous, vigorous activity and the squishy sounds of water and soap. It doesn't even require the sound of continuously running water (which would be a waste of resources). In some senses it's little different than a parent who detects you've left the bathroom without washing your hands - no sound of running water after the sound of the toilet flush. Except in this case it also has motion detection; handwashing certainly has a distinctive, detectible pattern of motion.
Yet try rubbing your dry hands together, as if you were washing. The timer doesn't start - it depends on a combination of sound and motion that if not present, doesn't trigger the app. That's a fair bit more sophisticated than "Hey Siri, start a 20-second timer."
It does no "scolding" whatsoever unless you turn on the
optional Handwashing Reminders setting, which is off by default. If you tell a machine to remind you, it will - don't blame the machine for doing what you've instructed it to do.
Even so, a reminder is not a scolding. The reminder doesn't say, "Oh, you dirty, unsafe person, go wash those hands this instant!" Does it keep track of failed/interrupted washings? Does it set a daily goal or "reward" you for doing well with monthly badges like the Activity app? No, no, and no. No faux fireworks display, no mocking sound effect if you fail to finish. It counts down when it detects handwashing-like activity and indicates when you've finished the task.
It has started counting a few times when I've rinsed items in the kitchen sink, but it also abandoned counting when that rinse was short-lived. No "Why did you stop?" indications, no "Finish what you started." It just quietly went away.
I really don't get your problem. It's not some sort of parental authority that you can't escape. If you want some help with thorough hand washing, you use it. If it's too thorough for your own taste go into the settings and turn it off.