I actually work in a consulting company’s forensics practice, and with reasonably available tools, you just can’t get anything after it’s been overwritten once.
I suppose if you wanted to, you could find some outfit with some kind of gizmo that could possibly reconstruct it, but like ** Msmith537 ** says, it would just take too long and be too expensive to be practical. After all, we charge upwards of $250/hr, and I can’t imagine that an outfit capable of doing something like this would charge anywhere near that low.
Generally speaking if it’s overwritten, it’s gone. One pass should be fine.