At a minimum, shops should have some short documents that explain where the code is in source control, what is needed to build it, where it got deployed, and so

At a minimum, shops should have some short documents that explain where the code is in source control, what is needed to build it, where it got deployed, and some general idea about how to do a full system test. Call it the "Hit by a bus" doc if you want. Or more nicely -- the new hire orientation doc. And it's management's job to ensure it gets kept up to date. Because it's a business continuity issue.