I agree, the analogy is imperfect, because you don't pay interest unless you need to extend or maintain the code. It's only useful in a world where the codebas

I agree, the analogy is imperfect, because you don't pay interest unless you need to extend or maintain the code. It's only useful in a world where the codebase in question is under ongoing development, but those are the situations where I've used it. Naked calls work fine as an analogy in the case you describe.