Particularly when you haven't seen countless thousands of other faces in the meantime. As an anecdote, I used to work with large groups of children (summer cam

Particularly when you haven't seen countless thousands of other faces in the meantime. As an anecdote, I used to work with large groups of children (summer camps & sports programs). I would allow myself one day to learn all of the new kids' names, which was > 50 at the start of any new thing. I don't remember all of their names now, after 10-15 years, but I assure you that you could give me a lineup (of them at the time) and I could pick out the kids I worked with. Hundreds and hundreds of them. I wouldn't have a 100% success rate, no doubt, but I think a very good one.