What big means is it really does come down to genetics. There are a few people who have grown to enormous proportions on no more than 200 grams per day. Granted these are the genetic elites. We all know that one guy that drinks coke, beer, and liquor, and eats twinkies and fast food all the time, sleep 2 hours a day, and grows on 200 sets per bodypart. Its all based on our recovery ability, how hard our jobs are, how much sleep we get, our mental state. If one guy works a desk job, is single, and is relaxed at home, he may not need as much protien to grow as the guy that works 10 hours a day in construction with a wife and 2 kids, who barely gets six hours, who needs a large surplus of nutrition to be able to recover.
The answer is however much protein you can eat without getting ill. So long as you are producing enough HCl, or supplement with it, and you have enough fat present at the time of digestion. Your stomach size and your ability to digest the protein and absorb the amino acids is your limit. Your ultimate limiting factor is your own body. Could be 25 grams, could be 250 grams.