I'm not smug about any aspect of my parenting skills. But I really have never punished my children.
I had severe issues as a child, smacking, punishments of various kinds, and that led to a very troubled teenage time, and leaving home early, and into abusive relationships.
I have read many books about talking to children, and getting the best out of them, recognising negative emotions, and how to discipline without punishment.
It works. As a result of no punishments, there is very very little bad behaviour of any kind, as my kids know any mistakes they make, will not be punished. They talk a lot about things, and tell me often that other kids in their class wouldn't dream of telling their parents these same things.
It is not by any means smug or far fetched. We just talk. A lot.
My SIL believed in punishments, and was constantly taking things away, limiting screen time, taking away favourite activities, and both her children were very badly behaved, so clearly it didn't work. Not only that, they were liars. To avoid punishment, they learnt to lie, not learn how to be good/decent human beings.
I feel very very lucky however, as I have large age gaps between my children, and Boy, Girl, Boy. As a result, they don't fight, or squabble as there's nothing to squabble over.
I think as a parent, we may need to use various techniques and it's not one size fits all. All children are different. Also, we can all be the perfect parent when we're all calm and nothing stressful is going on, but it's not easy when life is shit, and things are going wrong and something is just the last straw.
Again, nothing talking can't fix.
If a child has hit a sibling, get them to write an apology (if they are old enough to write), do something nice for them, make something nice for them etc ....get the punishment to fit the crime.
Get them to see what they did was horrible, and they made that person feel bad. I just don't always see how an example like that, results in no TV time. It just builds resentment for the sibling, and doesn't fix the problem that hitting is wrong.
Again, my SIL's kids hit each other all the time. So much resentment built up, and then they would hit each other without anyone seeing, and then lie about who did what so then the punishment wouldn't happen, as no one knew who to believe.
We all have unique circumstances though, don't we, so I'm not judging. But smacking for me, that's very black and white. It's just plain wrong.