If the potatoes are shredded..(½ the thickness of a pencil or thinner), and pressed into a patty, they will be cooked just fine when they are brown on the outside. If they are in small chunks, they must be stirred a bit, and kept 'mostly' to a single layer in order to brown/cook evenly. It's really pretty obvious even the first time. Just keep the oil hot and don't leave the pan unattended very long.