Many technicians question the value of making a mini bulls-eye when repairing cracks. The reason for creating a mini bulls-eye is to help reduce the effects of the stress in the crack.
Stress is a function of force divided by area.
The larger an area is, the lesser is the effect that a force can have on it. A bulls-eye has a greater area than does the end of a crack. A mini bulls-eye placed at the end of the crack will reduce the effects of stress and act like an anchor in the crack. Drilling the glass alone will not create a solid area throughout the entire layer of the glass. Just drilling a hole will leave a small portion of the glass intact near the PVB layer.