We spanked our children according to how FoF (Dobson) taught. One was never supposed to do it in anger and it was better not to use your hand for it but a wooden spoon, and it is reserved for acts of defiance against boundaries which have been clearly stated (never for childish irresponsibility such as spilling milk or breaking something accidentally).
Now that I am older with 4 of our 8 children grown, I might change some of how we did it. But our 4 grown children are all law abiding, tax paying citizens. So despite our flaws (which are many), we must have done something right with the discipline?
We have Christian relatives our age who had a liberal education and were very anti-spanking. They also homeschooled straight through and were very involved with church and awana and whatnot. So, they were a lot like us, only we spanked and they didn't. 3 out of their 4 children have had drug problems and problems holding jobs. One appears to be permanently brain injured from the drug use (delusional, hallucinations, had to move home to be cared for).
I would say, especially for children 5 and under who cannot think abstractly that if they are in danger of self destruction, they must experience pain and fear such that they will not try that again. And for my children, a couple stinging swats with a spoon on the fatty part of the butt (not hard enough to leave any marks) was enough pain for them not to do it again.
So, pre-school child runs into the street- spanking. 2 year old tries to stick a paper clip in the electrical socket- spanking (or I remember swatting their hand because my children tried it as soon as they could crawl). And I distinctly remember several of my children shop lifting at young ages- spanking , AND if they made it home with the item they had to go back and confess to the clerk (who made a big deal about forgiving them since they were honest instead of calling the POLICE)!