A methodology that incorporates all manner of junk data produces junk output. (judithcurry.com)
Depending on how much junk data is on your drive, this step may take anywhere from a few seconds to a few minutes. (pcworld.com)
The drive can overwrite its memory cells with junk data so it can't be read or send an electric pulse to flood the memory cells and burn them out (scientificamerican.com)