I worked at a trading firm where you could add a zero to that cost for a 3-hour outage, and I can tell you that the one thing we would absolutely never skimp on was code review. Because the cost of a bad "fix" that actually makes things worse has the potential to be greater still, and because humans are most likely to make silly mistakes when they're working under intense pressure.

What we would do instead is slightly intensify the code review process by pair programming the hotfix, and ensuring that a third developer who was familiar with the system in question was standing by to follow up with an immediate review.