I used the machine-shop analogy somewhat loosely, because obviously in the world of CNC there is a huge amount of “software development” of an entirely different kind.   (Yet it is subjected to very rigorous methods because it does translate directly into what is done to precious industrial metals.)

P.S.   There is never really any question when a machined part goes to the scrap-bin.   If it is off by a “tenth” (1/10,000 of an inch) in a crucial operation, the whole thing can be scrap.   And the computer software which we write might well be subject to equally-stringent standards.   Or, more so.   (If you don’t believe me, just utter the phrase, “patient health and safety issue,” in a medical-software setting.   It’s roughly equivalent to shouting “Fire!!” in a crowded theatre.)

Still, the essential idea is that of “scrap.”   And, the fact that we fairly spew it out.   Sometimes, I wonder if we mistake activity for progress.   Are we ever intending to be “finished?”   Are these processes really what our customers and employers want and need?   Or could we be more (self-)satisfied about them than they are given good reason to be?   Introspection never hurts...   we should be asking ourselves the hard questions.

And I wonder when, I’ll be home again, and the morning answers:   “Never.”
And the evening sighs, and the steely Russian skies go on forever.
– Al Stewart; Road to Moscow.