Each one of my dogs have learned or been trained differently. I have yet to have two with the same personality, behavior, or patterns. Even with the basic commands of sit, come, leave it, your done each one has a different reaction. I tend to try and teach or train each dog enough to keep them safe and the rest they learn on their own. Most of the time I think they are training me!
As for the growling I agree that in and of itself it is not necessarily bad. I had a Queensland Chow mix and lived in an apartment where barking would no have been appreciated. My girl would bark and I would correct her and tell her to use an inside voice. Her inside voice became a growl and we went with that. Now when the growl became deep and the hair on her neck stood up, like when a cat walked across the fence, you knew she was giving an aggression warning which was followed with a your done command.