Security through hopes & prayers...
A friend used to have a combined live/work space for his photography business, which meant he'd often have visitors hanging around the studio at all hours and in all states of self-restraint/trustworthiness. Since this was also in the pre-smartphone era of 3G mobile communications, it wasn't yet the case that everyone had an always-ready device in their pocket for accessing their online presence (and even if they did, said access was slow enough to be a deterrent), so whenever people happened upon a computer with a fast broadband link it was often seen as an opportunity to "check my email" & so on.
So, the incentive was already in place for unauthorized persons to access the computers scattered around the space. Not that they'd have malicious intent, by any means, but there was still the possibility of significant accidental harm. See, the friend in question had a stereotypical artist's approach to content management & data security:
PCs had a single account with Administrator access, which was always logged in. (Probably auto-logged-in, except in the latest few years of the setup.)
Project files for a given Client N were invariably (a) on the computer desktop, (b) in a folder named "New Folder (##)" (nearly always a 2-digit number, because there were that many), and (c) open-and-unsaved in whatever application was being used to work on them.
Every application that had ever be opened on the computer since its last restart was still open, and almost certainly had unsaved files. Very frequently, unsaved newly created files, so you couldn't even safely exit the application without assigning a filename and directory location to a bunch of "Untitled Document N"s — which nobody but their creator had enough information to actually do.
You almost couldn't avoid messing something up — even I, who had set up and adminned all of the systems there, couldn't avoid stepping on land mines, because it wasn't a question of technical knowledge. To safely "jump in" on a machine that had in-progress work active on it, you had to know the intent for a lot of things that gave no indication as to their intent, because that information existed nowhere except inside the mind of the machine's owner. (And honestly, i often questioned even that.)
Suffice it to say, it was not an environment where you wanted other people messing around in the session, no matter how innocently.
Eventually, I picked up on all this, especially after being around long enough to start finding predictable patterns in the goings-on. On the eve of one such occasion, at the point where "work time" had been suspended and people were arriving to the space for an evening social gathering — always my cue to depart — I very pointedly and conspicuously told him, "I'm done on that machine, so you can go ahead and log out." The response I got was, "It's fine, everything is exactly the way I want it." Okey-doke. I did my part. Off I went.
The events that followed I only learned of days later, when next I arrived to the space. In a scene ripped straight from the pages of Predictable Events Quarterly, what had happened was:
1. The chosen approach to securing the computer "exactly the way [he wanted] it", rather than logging off, was to switch off the display. And nothing else.
2. At some point, some visitor that evening decided to go looking for a computer where they could "check their email".
3. Unfathomably (except, totally not in the slightest), said visitor spontaneously earned a degree in IT management, and worked out how to switch a screen back on. They were thus undeterred by that impenetrable barrier to their accessing the machine.
4. In bumbling around attempting to reach a web browser, they closed some application (which was no doubt running fullscreen and getting in the way of any attempts to access other software), accidentally destroying several hours' worth of unsaved work.
...And I had to pretend to be shocked and appalled by this completely unexpected occurrence, when all I really wanted to do was spray-paint "I F---ING TOLD YOU SO, IDIOT" on a frying pan and repeatedly smash it into his thick skull.
