[pc86]

Sort of, but imagine this scenario:

I very rarely have issues in problem space A, but I don't really test for A. Maybe a few here or there but it's a small minority of my tests and the coverage is probably just incidental. I test heavily in problem space B for whatever reason.

I get hit by a bus, and you're my replacement.

You have no experience with problem space A, so there are few if any tests around that space. All of a sudden the coverage is misleading because we might have 100% coverage or close to it, but the thoroughness isn't there and suddenly releases are less reliable and support ticket volumes increase.