The short answer is 500-1000. QBs, especially rookies, typically have this level of autonomy. According to Pro Football Reference, each NFL club has run between 947 (Cincinnati) and 1178 (Philadelphia) offensive plays through 14 games this season. The offense runs 67-84 plays each game on average. Assuming every play takes about the same amount of time, this means that most quarterbacks can call their own number within this range 1-3 times per game. In addition to calling his own number, a quarterback will usually call a pass play or two when he feels the situation calls for it. This is another opportunity for him to show what he knows about the playbook so there's no doubt where he wants to go with the ball. Finally, he may choose to use one of his remaining opportunities to take a knee or throw an end-around instead. Overall, I'd say most quarterbacks know around 500-1000 plays during their career. This number comes from directly observing and interviewing dozens of former quarterbacks over the years. As you might expect, not all players call their numbers in the same way. Some are given the job and left alone to make their own calls while others need more guidance from coaches or teammates. A few even claim they don't remember any of their plays from years past. Regardless of how many plays they know, every quarterback should be able to identify their primary options based on the defense they're facing.