The issue is that an engineer’s definition of done is the perfect set of code, and left to his own devices, an engineer will endlessly improve the code on the mythic journey to done.

You know, I've heard this repeated endlessly by numerous managers, technical and not, with whom I've been associated, and, frankly, in my experience it's bullshit. No responsible engineer (hell, no irresponsible engineer) that I've ever worked with has exhibited this tendency. They, and I, have all worked on code until we're satisified that it meets the requirement and passes basic validity checks, and then it's handed over to QA.

This trope about 'if it were left to the engineers, nothing would ever get done' is, if you ask me, simply an excuse for managers to justify their existences. I'm sure something along those lines was muttered by one of the shits in a suit who pushed Columbia onto the pad in the middle of winter.