Ok. After more experimentation, I understand your point. Basically the question you are asking me is "why should I iterate over the last part of the list that may not exist?"
So, what I need to do is change the list at the end of the map, to a list that will be used to count the new elements, rather than counting all of the elements in the original list.
While I still disagree with you about "right" and "wrong," you have made a valuable point which makes the map more efficient. Thank you.