not necessarily. If it is hard for the dogs to hang on to, they may improve their grip correctly or compensate incorrectly.
the instinct for some dogs is to dig in with their canines, but if they don't have a full mouth grip that puts an immense amount of strain on the canines.
I'm working with Riggs on that now. He prefers to take 3/4 to half grips on the tug and the psring pole. Once he is on the spring pole he switches to a one side of his mouth grip. I make him out every time his grip is less than ideal.
I think you should move this thread to the training section