[dark-star]

> At some point in the past it used to be necessary to do many overwrites

Even that has almost always been just a cargo cult. Some people (mainly from the hacker community) claimed that US government agencies can still read data from harddrives that have been erased. It has never been proven by any independent data recovery company.

It might have been somewhat true for MFM or RLL drives (these were before my time in IT), but at least since IDE drives, it was no longer true. However, the cult around "multiple erase cycles" still held, mainly because of companies like Norton etc. who sold snakeoil tools to "securely" erase your data