Upgrading versions of a framework with breaking changes is one. I did a 12k PR a few weeks ago that touched almost every file of the app. It was an all or noth

Upgrading versions of a framework with breaking changes is one. I did a 12k PR a few weeks ago that touched almost every file of the app. It was an all or nothing thing, as almost every third-party dependency we used had to be swapped by something else. At least we have amazing test coverage, so it was easy to find bugs. But there wasn't much I could say other than "trust me".