I would agree that different things work for different kids. Don't take a kid out for errands and expect perfect behavior without proper rest, food, etc. Just asking for trouble
Also agree with say what you mean and mean what you say. Do follow through with a consequence cuz your kiddo will know you mean business.
I do believe kids are more aware and can/do know more than we give them credit these days. Kids can behave if EXPECTED to behave. It's all in the expectations and in the respectful approaches the parents have in showing them that. No matter if it's a spanking, a time-out, a withdrawing of priveledges---just be respectful about it and consistent. They'll get the message.