I don't have children and I am not the product of a "humane spanking" parenting model. My experience is limited to what anyone nowadays would call abuse. There were daily "spankings" with objects, open and closed fists. The "reasoning" was limited to nonsense from the likes of the Youth book.
What I can tell you is I was a skeptical child, always needing a reason to agree or believe. My abusive parent punished corporally for refusal to agree with wts doctrine, physically defending myself from bullies or even just having the wrong look on my face. It was a daily event.
I do not love this parent, to this day.
My UBM parent did reason with me and it worked.
Pretty much the theme was, "Yeah, when I was your age I used to think my parents were so old and I was the only one who [insert whatever event had happened that included me acting up]. But then I realized I was wrong. Kids are all the same no matter what generation they're in. It seems like a big deal now but it won't in the future. All you have to do is wait. Now you can keep acting up but it won't make anything better."
I remember talks comparing children to beasts in the field who "needed" to be beaten to learn--there was no other way to learn. I used to quote scriptures that said not to exasperate your child, and then be beaten for that!
I would be interested in learning from (now) adults who were lightly spanked, "appropriately" (if there is such a thing).