Yeah, depending on the particulars of a system. If you're at a startup and report to the CTO, that might be perfectly fine in an emergency. At a company with a few million users, almost certainly not. There's a spectrum of possibilities.
In an emergency, that sort of thing even happens at Google (more for their smaller services, and almost always in the form of auto-LGTM hot-fixes bypassing the normal checks rather than actual live-editing of a script or binary, but even that latter thing happens occasionally). There are checks and controls, but an emergency for a billion users is a big deal.