When I worked in the aerospace industry in Saff London, almost every company had display cases of jewelry in the foyer. These would be composed of immensely complicated components in titanium and ally alloy and stainless steel. (The company I worked for took a 1500 lb slab of aluminium in, and sent it out as a 35 lb cockpit frame for TSR2.) The cognoscenti knew that all the components on display were scrap. If they had been good 'uns, they'd have been sold. The bigger the display...
There is one Vincent factory picture which shows three engine builders, each behind his bench with a motor "in progress". Running the length of the three benches is a long table with barrels, crankcases and so on laid out on it. A former works employee, asked to interpret (not by me), explained that the bits on the bench were those that resisted attempts at selective assembly. They would go back to the shop for rework. Right now, they were scrap. (In the Rudge factory they would have been booked in as "spares"...)
At one time Harley Davidson engine builders drew all the parts needed for a week's engine building on Monday morning. Blessed was he whose engine was build on Monday. And cursed he whose engine was built on Friday from the detritus... Don't crow too soon: Black Shadows resulted from assembling together Rapide parts that were close to design dimension. What happened to the parts rejected for Shadows?
What has happened in the last 60 years is that factories no longer run machine tools clapped out by running 24/7 from 1939 to 1945, and that CNC machine tools can compensate for tool wear as they go along. But so long as you know that wearing components may be best replaced in pairs, because they were built in pairs, an undersize piston with an undersize liner, there's no problem.