Sounds like a good question, unfortunately I almost never actually replace parts anymore. I only do diagnostics and even there I have an assistant that hooks up the tooling I require. About the only bolts I turn anymore are those involved in doing wheel alignments which I usually do 3-8 of a day.
I like doing alignments as it is the last "tunable" item on a modern car. I get great pleasure solving problems through adjustments.
The last 104 we put connectors on I happened to be standing next to my assistant and I did notice a manufacturing difference between the new end and one that he had already replaced. I will have to take a better look next time. Sorry I don't have a better answer.
Bosch Master, ASE Master, L1
33 years MB technician