BTW It can take a very long time if the drive is faulty.
Ok - ok - I do leap in sometimes…You have formatted the drive so shred will not work. There is an app out there called Nuke (sometimes called dban). Try that… I personally use Hirens boot disk for things like that and a lot of people will not approve.
The trouble with failing drives is that you never know how the drive firmware will treat failed sectors. If you are extremely paranoid, you have to physically destroy the drive because it’s always possible the firmware will stop writing to failed sectors entirely, and your data will be left after running an operation like shred.
I wouldn’t be that sure about that article, professional ways to recover data from a disk involve some magnetic shadowing or something (you can see 7 or 8 writes back) so 100 may be an overkill but 20 would be quite sure but it will still take hell lot of time.
Not being sarcastic, how much the usb drive cost vs. sensitive banking data.
In this circumstances and if your paranoid that someone can obtain information from this hardware better to just use the hammer. My feeling is if the drive is faulty there is a big chance that there will be a failure in erasing the datas stored.