hot plate

Question

In a previous post you allowed a hot plate to be used if used before Shabbat. Does this apply even if the food is yet not cooked? If yes,why is this different than an stove top without a blech-both are the normal way of cooking, for even though the hot plate has a coverd heating unit this is the normal way it cooks and should not be considered a "heker". Or were you only talking about reheating fully cooked food that does not require a "heker" or blech? Thank you