Apple doesn’t just deploy to the whole world in an instant though.
First it goes to the private beta users, then the public beta users, and then it slowly rolls out globally. Presumably they could slow down the roll out even more for a risky change to monitor it.
Sure, but still whoever wrote the patch had his ass on the line even shipping to a batch of beta users. Remember this is Apple not Google where the dude likely got promoted and left the team right after pressing click :)
First it goes to the private beta users, then the public beta users, and then it slowly rolls out globally. Presumably they could slow down the roll out even more for a risky change to monitor it.