Simple. If you are detected by a watcher, and you kill it before it calls reinforcements, that should stop it from calling reinforcements.
Why is this not a thing? It's completely impossible to solo those loot chests in the Leviathan, because to do so you'd have to kill all watchers in the room within seconds of each other, which is completely impossible by yourself. Even if you kill a watcher BEFORE it detects you (as in there is nothing in the feed saying you've been detected at all, even after it's dead), it STILL calls for reinforcements anyway.
I've spent almost the entire raid with a group gathering these keys, why do I have to spend even more time with them to actually go and collect my rewards?
-
It's as if you're supposed to do a 6 man activity with six ppl.