If I were a coach I would be tempted to get two QBS every year. It is such an important position to the team and also probably the hardest position to get right. So many QBs can look good against high school competition but then just don't make the step up to college level of play.
In 2017 we had Zeb Noland, Devon Moore, Kyle Starcevich and Kyle Kempt. Imagine if Kempt had not emerged into a fairly respectable QB for that one magical year. But you don't want to leave your entire season's results relying on a prayer. The more QBs you have, the better chance that at least one of them can produce. But I also do understand that if prospects see you already have 7 QBs on the team, they would be better off going to a school that only has 3 or even 4. So, in reality it likely is not possible to take 2 every year. Wow, this is hard! I would need, like, a million dollars to figure this out!