Thanks a lot for the elaborate reply. I do tend to break things up into small functions. Why is that over-engineering? It makes it easier for me to reason about my code. It also makes it easier to refactor sometimes, although of course you're now restrained by the function's construct, so it becomes more difficult to move things between functions.

Do I understand correctly that you tend to make large functions because they're easier to refactor (and not returning early makes this easier)?