Final answer:
To maintain freshness and ensure efficient use of potatoes, the existing potatoes in the hot holding drawer should be slid to the left and newer potatoes added to the right.
Step-by-step explanation:
When the next tray of cooked baked potatoes is removed from the oven and placed in the hot holding drawer, the potatoes already in the drawer should be slid to the left and the newer potatoes should be added to the right. This method ensures that the older potatoes are used first, following the principle of first-in, first-out (FIFO).