What is the main value of making a head check before changing lanes?

Making a head check before changing lanes is crucial because it allows you to see areas that are not covered by your rearview and side mirrors, specifically the blind spots. These blind spots are areas behind both your left and right sides where vehicles may not be visible. By physically checking over your shoulder, you gain a clearer understanding of the traffic conditions around you, ensuring that it is safe to change lanes. This practice significantly reduces the risk of accidents by allowing you to notice vehicles or cyclists that may be in those blind spots. Recognizing the importance of this maneuver enhances your overall driving awareness and safety on the road.