Both of my children have been through a 'hitting stage' and during that, both of my children have each received a single smack from me, followed by a discussion of how it made them feel and why they shouldn't hit people, because it makes other people feel like that too.
Beyond that, I see no value to it. All it teaches them is fear of consequence, not what they should or shouldn't do.
Parenting by the 'be-good-or-I-will-hurt-you' book doesn't seem very useful to me. Although like many on here, I took a few smacks as a lad, it taught me little about my original offence other than to be more careful not to get caught next time.