You're right, we did this a lot at Boeing. I am very proud of the fact that none of my designs needed to be modified once the metal was cut, and it all passed test and certification without any problems.

Software development, on the other hand, lends itself very well to iterative development. You don't have problems like sinking a new forging die costing half a million bucks, so work really diligently to not need to scrap a die. Keep making mistakes like that, and Boeing will move you to a position where you get to design ash trays.

D is very much an iteratively developed product.