i agree with Doug.
as a former machinist, [45yrs worth, and still practicing !] the object is to make items to blueprint spec.
the newest and best machines out there [even five years ago] brag about how great they are at finishing items to the 0.0000 tolerance, and even self correct for tool wear as well as detecting tool breakage, stopping the machine when breakage is detected, or tool wear is at the limit of the tolerance.
my opinion is there is absolutely no reason reworking of items should be needed if bought from a reputable source with modern tooling.
mistakes can, and will happen, but there is just too much reworking needed anymore on a lot of different items, that should absolutely not be needed.
the only thing a guy should need to do is clean, inspect, and install. [unless you are like me, and try to save everything cast off by others, like abandoned dogs. i like dogs better, that's why i didn't say cats. ]
just a crabby old man mumbling in his oatmeal.
your mumbling will vary..............