The basic rule is to do no more than you need to do, no more than what works. And as the trainer told the lady in dog class when she asked how firm of a correction to make, 'To YOU, it's going to seem like a huge correction, because right now, you aren't making ANY corrections'.
A person has to know their dog and learn how it will react. I have one German Shepherd that is really sharp, distractible, high prey drive, I have a Collie, that if you frown at it, it goes into the bedroom and hides under the covers. If I handle one dog like the other, it's a disaster.
All the principles, the basic timing, everything, of training never vary, what varies is, how far up do you go up the ladder. It's just like a horse. When it's trained, you can make him go faster by just pressing your feet against the stirrup treads. If he doesn't react to that, there is a next step you go to; there is with all animal training.
Say I am heeling my collie. He 'Does a Doug' (Dog from movie, 'UP'), I say, 'bert, watch me'. We're done. That's all he needs. If I hadn't trained him for four years, I can probably just move the links of the collar a little, I don't even need to make a correction. He already WANTS to pay attention, but I taught him to pay attention by offering him a treat, AND correcting him when he did not respond.
But I spent four years training him every day. My friend's collie, she hasn't worked with like that, she was very erratic in working with him, and she could give him collar correction that would spin a wheel off a truck and he is at the end of the leash, barking and leaping.
He's also a different dog. He is extremely different from my dog. There IS no collie like mine. Mine is a rock, he is just like that. He's so easy that it is embarrassing. Same breed, very, very different kettle of fish. It takes a lot more work with hers, he's more distractable, he's far less steady (does more different things within a given time period). To a point, that is inborn. It is VERY hard to get something out if the Dear Lord didn't put it in there.
If the dog responds to a frown, that's all you need to do.
When it responds to nothing, you need to do a whole lot.
Dogs test out their role with play dominantion. Next, if they get away with that, comes serious domination.
I don't punish dogs for playing. I punish them for not responding to commands.
If a dog is tearing around and barking, I say 'SIT' and it doesn't SIT, I punish it. WHAT punishment? 'That depends'. Not one iota more than needed.
