Then it turns out that your CI gates are green because your tests are all subtly broken, the code you've been reviewing doesn't matter and the code you haven't been reviewing is what's broken in production. You learn from that and rebuild the universe, but now you're compute-limited from rebuilding your agents to deal with the underlying issue in your tooling and you have to dig yourself out of a hole you dug with a large derrick using nothing but a shovel.