downvoters: I'm deadly serious. I've seen plenty of deployment systems which were unbearably slow because it gave more time for a human to spot a bad deploy and cancel it, and who were afraid to replace it with something faster because it would lack this safety net.
That they deployed a broken config file & forcefully stop-started nginx instead of reloading it (and bypassing nginx's built-in protection: it will test a config and refuse to load it if it's broken on reload. on restart it's stuck with whatever busted config you give it).
How is this specific to Nginx? This same mistake is possible with any other software ever written.