Your question is too wide interpretable to be sure what to answer.
As a first general guess, I'd say that a shovel has finished when the hole is deep enough.
In metal, a drill is easier, and I drilled the hole in the steel block part of my chain breaker kit to such a depth that I can't hammer the chain links pen completely out of the last link plate on the other side.
Because it's pretty hard to hold such a small long thing and the rest in place to hammer it back in.
See, I don't throw away the excess parts of the 1/4" Regina 420 motorcycle chains.
I keep them until I have enough to assemble the required 105 links.
My 3rd last chain was such an assembly, and it did the job like the others did before and after.
See, that's a benefit of such thick link plates, one can hammer a pin back, something you won't try with the fragile cut out (for the Lightweight Religion) link plates.
I also did that with Gussets 3/16" bicycle "tank" model chain, also with no problems.
Instead of binning what is too much, I use it, and avoid a counter passage