Windows Explorer gets your particular example right: When you copy a bunch of files into a folder, it will highlight all of the copied files after it is done, so it doesn't matter if you saw the progress bar or not.
However, this was a trust thing, and not an innate limitation of human capacity.
Now that we’re in 2020, I would argue that almost 0 users need that crutch.
If the work is done, it’s done. Similarly, employees on early keyboard-only terminals didn’t need any delay either. They trusted that when they said do X, the system did it. How else could you process dozens (or hundreds!) of items a minute?
Hmm, perhaps if you replace the word "latency" with "duration"?