I grew up with two extremes; a step father who used the belt, and a father that used consistency.
It got to the point where corporal punishment was not effective for me as a form of discipline. I viewed it as unfair, and it made me lose respect for my step father. My transgressions, I thought, were never on par with the punishment doled out to me.
Now, if my father was visibly upset with me, I knew I had pushed it too far! He shook me once, I think I was around eight years old...I never forgot that. For him to be that PISSED that he would actually do that affected me more than anything, because he never resorted to laying a hand on me.
My step father was always pissed enough to hit me, so it meant nothing. But when my father got to the point of laying a hand on me (even just to shake me), I knew it was serious.
I will use time outs and consistency with my children.
oddball is right, too. Both parents must be on the same page in terms of discipline. I've seen it time and again where one parent is way more lenient with the children than the other, and at that point, the children hold all the cards. In addition, when a time out is given, or grounding, there should be no "letting them go" halfway through the time out or grounding...if they do the crime, they should do the time. All of it.
Rules need to be consistently enforced, and time outs given on a consistent basis. If you say 'no' and allow a child to whine and bargain a 'yes' out of either parent, you are setting yourself up for disaster. In addition, rules should be fair and not too many; parents need to pick their battles!
Children learn very, very quickly how far they can push the rules, or the parents. From the time they are toddlers they are testing their limits.
They will play you like a fiddle if you let them.