Not in my experience...
In my experience, the core numbers are used to identify what cores are used in each mold....
If they find a defect in the castings, they need to identify which core is the bad one so they can sort out all of the potential bad ones from the stock and then go fix the mold that's causing the problem...
With the volume of blocks that they have to pour, they can't keep up with demand with only one mold... They have many molds to keep up with the production demand...
They need to be able to identify what particular mold is causing the problem.. If they can't, then they have to go over ALL of the molds (even ones that may be good) to make sure they catch the problems... If you mark each mold, then you can isolate which cavity/core is causing the problem and narrow in on it much quicker...
It's a quality control thing... The core numbers are for traceability...
