I think I had that exact one once early on. I did actually get an "if you could go back in time a couple years, what advice would you give yourself?" a little while ago, which 1) threw me, because I wasn't expecting much of that formula crap from this place, and 2) I hadn't prepped for, so I just punted, being able to think of very little other than things unrelated to work but also lame, cliché, or "don't interview at that place, you'll have to answer a dumb question and then you'll feel like an asshole when you can't". I tried to deflect with a joke but it didn't work. Oh well.
I've consistently gotten the "tell me about a time you fucked up" and "tell me about a time you worked with a douchebag" ones. And simple "tell me about a time you disagreed with someone at work"-type ones. Not every interview, but often. And unless you've actually had an experience that happens to make for a good answer to those, you've basically got to make something up. Even if you have fucked up tons of things and worked with a bunch of douchebags—the questions are weird because if everyone answers totally honestly some people will have way better answers, especially if they're also good story-tellers, because they've been lucky ("lucky") enough to have had an experience fitted perfectly to a good answer for those questions.
Even for the simple "time you disagreed" one, I don't exactly file away details about little disagreements in my head, so I can't form a satisfying tale from those—almost all of which were pretty boring anyway—sorry, so here's some made up bullshit again. Which will be better than most people's best honest story anyway. What the fuck was the point of these, again?
[EDIT] I actually think being a smidge less psychologically stable and well-adjusted might make it easier to answer some of these! Hahaha. Shouldn't have read the Stoics so much in high school, I guess.
[EDIT, responding to edit]
> I'm sure it made sense 30-50 years ago when people spent decades with the same employer, but anyone asking that question today is just indicating how out of touch they are with the real world.
Yeah the honest answer, based even on my relatively stable employment history, would be "somewhere other than your company, with a 15-20% pay bump (by the time I leave—30% over what you're about to offer me now), probably attained leveraging something I learned here". Just following the trend line here, don't blame me :-)