Wrapping potatoes in foil does not speed up the cooking time, but it does affect how the potato cooks.   For one, the skin doesn’t crisp up when wrapped in foil. We love doing it this way because we can control the amount of crisp after the inside has been baked.   The foil also acts as a packet that helps create and trap steam during the baking process. The steam makes the cooked potato much softer and fluffier compared to unwrapped baked potatoes.