Horses are very much like children. What works for one doesn’t on another. Sometimes a swat is needed, sometimes it is just a look, or a word said in the right tone. I have never found that harsh over- the- top discipline is needed when your basic foundation is good.
Our horses for the most part want to please us and do what we are asking. It is our job to ask in a way they can understand. To ask things of them that they are capable of doing.
My current mare at 17 has never been hit ( i raised / trained her). My 3 year old gelding has never done anything but try and do what I ask and my daughters 20 year old mare has never been disciplined since we bought her in 2010.
They do have opinions and test us at times but we work through it, we do not force them through with discipline and on them it works. I am heavy on praise/ affection.
I have had and ridden horses who needed a couple of swats with a crop on occasion or a couple of whacks on the front legs/ chest with a lead rope( while I yelled like a crazy person for 3 seconds) in response to biting me ( took 1 maybe 2 times of that–John Lyons methods).
All that to say that sometimes corrective discipline is needed and sometimes it will be forceful depending on the horse and circumstance, but in my experience with many, many horses it is not needed as much as is changing the way you communicate with the horse as an individual.