Just a comment having spent a reasonable mount of time in corporate R&D as well as manufacturing.
Most major manufacturer's have Final test procedures of some type. There are normally also different specifications supplied by the end user (say comp cams)
During the manufacturing two identical parts made at the same time on the same machine may perform differently for a number of reasons to numerous to list. So we have Final Test. This is where the completed parts are subjected to a variety of tests under different conditions and then sorted according to their performance. For example:
A "Bin1" part is the highest quality and consequently is priced at a premium.
"Bin 2" is slightly lower on performance and priced cheaper.
"Bin 3" is middle of the road on performance and priced cheaper yet.
"Bin 4" is still functional but may fail if exposed to Bin 1 spec's
'Bin 5" is a reject and gets recycled of scrapped

In addition, The end user say Ford, may require their own set of test parameters: In the case of hydraulic lifters it might be x amount of spring pressure with different viscosity's of oil under extremely hot and cold temps.

Blueprint engines may be buying Bin1's

Comp Cams may be buying a bin 1, 2 or 3 part.

the local parts house will likely be selling bin 4's as their house brand, TRW may be Bin 3's, Bin 2's and the

Joe Blows engine kit supply company is going to go for the bin 4's and probably other stock crate engine rebuilders.

One also has to keep in mind the current supply chain problems may have caused some deviation in acceptable quality as well

In closing I will also say we have 3 rethreading kits. 1 Snap on 185.00?, 1 Mac tools 125.00, and 1 Craftsman 59.00.
They are ABSOLUTELY identical in every way except for the label on the outside. Even the inside label is the same as is the box and its grain patter. Are these Bin 1, 2, 3 tools or are they exactly the same? only the Manufacturer and the buyer at the 3 companies know for sure