That is a good article, and the method works fine. I cannot question that at all. The only issue that I (and many others has) is these files aren't actually deleted. When one makes transactions, checks account balances, reads email (that sometimes one doesn't want discovered), that method isn't secure enough. Another user can easily use a tool such as Recuva & dig up a lot of info off that drive that the user "thought" was gone forever. It can be done remotely also.
A free app such as CCleaner wipes these files with the users choice of rounds (from 1, 3, 7 & 35). Of course, 35 rounds is overkill, as is 7 rounds. I use the DOD method of 3 rounds, this is plenty adequate to destroy the data. And as a general rule of thumb, it's best to go ahead and run CCleaner as soon as the user has completed their sensitive transactions.
I've bought used HDD's from eBay, and fortunately I'm not a crook, because with some of the info left behind on them, an experienced cyber criminal could put the pieces together and do great damage. I've seen HDD's with medical info, credit/debit card numbers, names & addresses, emails that I doubt that the user wouldn't want me to read. There are plenty of Linux tools to put the pieces of the puzzle together. So many PC part resellers openly sells used HDD's w/o bothering to wipe the drive. Usually, these sellers are power sellers, they sell hundreds, if not thousands, of HDD's a year. They don't have the time to wipe each drive. If they did, they'd have to pass that cost to the buyer, who is already taking a chance buying a used HDD. That responsibility belonged to the original or previous user.
However, for those who uses their computers for non-sensitive data, such as general web searching, school work, looking at the news & weather, streaming audio/video, forum visiting, this is perfectly fine. But when it comes time to sell, give away, donate or sell the computer as scrap parts, that HDD needs to be wiped. Mini Tool Partition Home Wizard can do the job, for free.
Cat