Time spent working on the wrong thing is not productive. How do you measure quality in software? If you need to measure quality in order to measure productivity, than one cannot truly measure productivity.

Or to describe this in practice: you can write prefectly modular, documented, tested and well written code that gets top marks at cyclomatic complexity checks. And yet, if you think carefully, your program can be solved by a quick shell one liner. Were you productive at all?

You don't need to measure quality, unless you want to achieve perfection. If you set your quality according to goals, you can ensure that no matter different software you write, it will need to meet same goals (same level of quality).