One of the biggest differences between the Pros and the Joes is that the Pros have the uncanny ability to put the clubface on the ball in an area the size of a dime. You an actually look at a pro’s well-used club and see the tiny impact area.
Impact labels are a good way to see where your swings connect with the ball. Clubfitters use these to help get the proper fit; teaching pros use them to made adjustments to the setup and swing.
At the range, I find these useful for diagnosis in whether I’m standing too close or too far from the ball. I also find impact labels useful for their immediate feedback. After mentally registering the “feel” of a swing, I can look at the tape and see where that was on the clubface. Knowing the “feel” in relation to where the ball hits the clubface helps me make mid-round corrections on the course.