That was just an illustration, not a recommendation. The guidelines are to eat enough to be satisfied, so counting or weighing your food is unnecessary. That's part of the beauty of this way of eating. Follow the guidelines and eat until you are reasonably full but not overstuffed, and you'll be fine.
Just remember to try to make them the same kind of potato, such as sweet potato or white potato.
“In the June 2006 newsletter I did not make clear enough the importance of monotony. As a result many people who tried the Mini-Diet introduced greater variety than I had planned by eating a different starch each day, rather than, for example potatoes everyday for 10-days. The fewer varieties of foods that make up the meal plan, the greater will be the weight loss.”