When grilling over hot coals and the meat may be cooking too quickly, it is often useful to have the option of selecting the "amount of heat" needed during the cooking process. To achieve maximum versatility, "grade" your charcoal with the heaviest amount of charcoal on one side of the grill tapering to lighter amounts on the other side of the grill.
By using this technique it affords you the opportunity to select the amount of heat desired by moving that meat either closer to or further away from the hotter coals while still allowing the cooking process to continue.