protein is more about when you consume it than it is about how much. protein shakes are good for immediately after a workout because muscles will start absorbing it as soon as possible after breakdown. and before you go to bed because that's when muscles do a lot of their rebuilding, but also the period when you're consuming the least amount of protein. if you have a balanced diet of 6 small meals a day with a fair share of protein, however, protein shakes are probably unnecessary.

i'm a vegetarian, so i kinda need protein from powders etc if i want to gain any muscle mass at all.