I’m not an X’s and O’s guy by any means, but I think this just comes down to film review, in game experience, presnap motions, and the skill of the QB themselves.
When you have a presnap motion that forces the defense to change, that will probably tell the QB which side of the field or which player will be the most likely to be open. If that player is not open, then it’s probably a check down or extending the play with a scramble or rollout. Additionally, one of your players might be covered, but the QB trusts in himself to put the ball in a great spot and also trusts in his player to make the catch. But most QB’s aren’t checking 3-4 options on every play. The defensive line will probably break through by then.