I don’t think smacking or spanking should be “losing your cool and hitting out,” but I think a consistent system of corporal punishment ain’t a bad thing. Kids need to know where the lines are and that there are consequences, and if a smack on the ear or rear does it then so be it.
The big difference is what is motivating the spanking. If you do it because you are mad then it’s probably not appropriate AT THAT TIME, but calmly spanking for serious offenses, especially if the kid knows a spanking will be earned from such behaviour can be a great motivator to avoid that behaviour in the future. Especially if this is followed up with a good talk about the offense and punishment.
My son will actually feel better after a spanking and our conversation afterwards, I let him know I love him, I hate to spank and would rather not but if he deserves it (and he knows if he does) then he respects my instruction and is motivated to not behave poorly in that particular manner again.
A talk, spanking, hug & kiss, follow up talk is a good formula for some kids. Sometimes nothing else can shock them out of a bad attitude into a more receptive mindset.
As a parent I definitely now know what it means when Daddy says “this will hurt me more than it will hurt you.” If that isn’t true then you might want to wait and cool down before you use physical punishment.
NEVER EVER threaten a spanking and fail to follow through though. You’ll lose all credibility with the kid and the threat will be ineffective from then on.