"Isolated" is a key word here. In a lake filled with stumps, laydowns, rockpiles, grass, weeds, etc., you have to find out why some are productive and some are not. There are a lot of other considerations that then come into play, time of year, water conditions (clarity, temp, etc) and the rest of the fishing puzzle. BUT.....all things being considered, you can drill down beyond cover to structure to help identify why they are where they are. That's what separates the bank beaters from the fishermen many times. But if either cover or structure is isolated it has a better chance of holding fish as a general rule.