...after you've completed a big job, whether or not you remembered EVERYTHING?
Like, you've had the car completely apart for months, and days after getting it back on the road you're suddenly wondering (while driving at highways speed) whether you fully tightened all the lugnuts?
I did a head swap on my Frankendiesel 4Runner this winter. Bought a crack free (rare) rebuilt head from a guy in SC. Had it shipped... cast iron, not cheap. By the time I had gaskets and everything, I was in for about a grand. Worked on it for a weekend straight, buttoned it up at 2am and fired it up. Worked like a champ.
I remember the next day, thinking "hmm, I wonder if I tightened down all the valve adjustment nuts. Then I forgot. Then I remmbered about a month later, but by then I had been driving it a lot so I just figured if they'd been loose, I'd have known by now. Was too busy/lazy to have look.
So...
I think it's gonna be pretty ugly inside. I was driving at highway speed when it started "ticking" then clacking, then it made a big CLANG and a magical puff of multi-colored smoke, then the tires locked up. All in about 2-3 seconds