I think you shouldn't do that. You need carbs in every meal and before working out!
Depending on what you would otherwise be eating for breakfast it could be more beneficial. If you are eating waffles with tons if butter and syrup a protein shake would be a better bet if you are eating a High protein high fiber meal you will get more out of eating real food. The stuff from protein shakes is highly processed which means you would be getting more out of it if you were eating it closer to its natural form.
Shakes as a meal replacement is ok in small, infrequent doses. Your body processes nutrients from natural sources better than artificial sources. Only drink shakes as a replacement if you absolutely have to, or on a time constraint
Lol that's the only way it's really effective... I either have a protein shake for breakfast or dinner as a replacement but I recommend adding things to it to make it more heavy either fruits, eggs, nuts etc. And trust me it works, but don't do it if you just need protein and are k or overweight ( I still need to lose 20 pounds)