I don't think I was ever spanked in anger. but it was one of those punishments (like having one's mouth washoud out with soap or grounding or denial of treats, what have you) promised for certain misbehaviors, and when we transgressed, spanked we got. 45 minutes of apology certainly never followed. To the contrary, we were lectured (far worse than spanking) on what the transgression was, sometimes why, and that we had brought this consequence on ourselves and that they didn't LIKE spanking us, but felt it was the right thing to do under the circumstances.

mostly it was the humiliation that caused this to become a deterrent, as I recall.