Or, why things take so long.
It would be forgivable to believe that as a product’s design nears completion the engineer’s job is pretty much done. If they did it well, there is a complete documentation package that production can use to build 1 or 10 or 100 of the item that was designed. But it is surprising how much engineering effort is required between design completion and hardware delivery. Production engineering is an often overlooked, but critical bridge between the drawings and the hardware. I have found production engineering to be of vital importance even in the early stages, before the first serial number has been completed.