Recovery from an overwritten file has essentially never been done. Or if it has, it has been kept top secret. There was one study a long time ago where a few b

Recovery from an overwritten file has essentially never been done. Or if it has, it has been kept top secret. There was one study a long time ago where a few bits were recovered with some accuracy with an electron microscope, but it was from a really old hard drive with a much lower density than current ones. Those overwriting regulations are just in case such technology might get invented in the future.