Yes, that's exactly what the problem with flash storage is. A single pass of overwriting all nominal storage is pretty close to wiping the entire disk - the spa

Yes, that's exactly what the problem with flash storage is. A single pass of overwriting all nominal storage is pretty close to wiping the entire disk - the spare blocks are limited in number - but with SSDs there's just no easy way to know what may be left behind on eventual bad blocks that have been replaced by spares. So-called "hybrid" HDDs that are fronted by a small SSD to give the impression of faster writes are subject to these complications as well.