"design is complete when there's nothing more that can be removed"
That reminds me of a story I was told back in the 1970s when I was a trainee TV engineer for Rediffusion.
When designing new TVs, they would build the prototypes with slightly longer legs on the components (usually the resistors and capacitors). Then, with the TV up and running, someone with insulated side cutters would come along and snip one of the legs of a component and, if the TV remained working, that component would be removed from the final design - if it stopped working, the TV was switched off, the leg resoldered together, the TV turned on and the process would continue with a different component. The TVs would then go into production with only the components fitted that enabled it to work.
Sometimes the removed component might have been doing something important in the long term - e.g. preventing a different part from overheating, compensating for the different tolerances in other components etc. Whether the story was true or not, I cannot say. But maybe it accounted for the booklet that was issued to all engineers. This listed all modifications that HAD to be made to various models of TV sets either out in customerland or if they happened to pass through the workshop and were found without the specified modifications. Most of these mods were to prevent known/regular component failures and burn-outs.