Shop by breed for dog food when your pet is unusual in size or he has nutrition needs specific to his breed.
Things to consider: Size of dog, special diet requirements, and how to find out what special needs your dog has.
Size is a Factor - Shop by breed if you have an extremely large breed or extremely small breed dog as their nutritional needs differ slightly from the average dog (and greatly from one another).
Get Specific - If your dog has specific nutritional requirements in his diet (say, his breed tends to be more active or is prone to joint problems), you might best be able to serve those needs if you shop by breed, since most dogs of same breed have the same specific nutritional requirements.
Knowledge Library - Dog books catered to rearing and raising your specific breed of dog are an excellent resource for finding out your dog's unique dietary needs. That way, rather than just buying them any old dog food, you can instead shop by breed.
