It's just an idea that you can use in an argument. When you invoke this idea, what you are actually saying is: "I want to prioritize this bug now, because my experience tells me it will save cost and/or effort." You use this rhetorical device to put weight behind your argument. It's like invoking "80/20 principle" or "technical debt".
Maybe I've become cynical but the longer I've been working, the more I like the postmodern theory that almost everything is a language game. I start to recognize bullshit, and to recognize when it's the right time to use BS myself. (Not saying that truth doesn't matter. Just that sometimes you have a correct but not convincing point, and you can support it with a not-100%-scientifically correct, but more convincing point.)