My opinion; If you have a poorly tillered bow with the limbs out of time, it won't send an arrow to the same place consistently unless you have it set up in a shooting machine with perfectly matched arrows.
Bows don't shoot themselves so you can't take the archer out of the equation. It has been my experience from some of my early bows that poorly tillered bows are very difficult to shoot as well as match arrows to. You can adapt to a bows shortcomings over time but why, when correcting the tiller makes it a joy to shoot.