Here is a helpful way to think about all this: imagine you lived in a world where every time you broke eye contact with something (including blinking, turning a corner, or even just turning your head), all of reality could fucking change. Hence, watchers, sentinels, and observers (which can take the form of anything from a security camera to a seagull or an owl to a human bystander) fix their vision on the entire field of action and don't break eye contact until it's over.