A loud “clunk!” means the throw hit the rim but did the ball roll in or out? They can’t be sure. Of course they may convince themselves they know how they are doing, but they don’t really, and if they throw balls for weeks they may become more confident—I’ve practiced so much I must be excellent!—but they won’t get better at taking free throws. Only if the lights are turned on can they get clear feedback. Only then can they learn and get better.
