You go out and do a purposeful hour long shoot, only to realize at the end that you've done the whole thing on ISO3200 by accident.
I did think of that. I went outside with an ND8 and CPL attached with the intention to shoot wide open. So, I never saw a low shutter speed, though 1/640 in broad day light should have clued me in. At least they are well exposed, which helps supress the noise a bit.
Five years ago my Canon 350D didn't even have ISO3200!
One of the reasons I loathe rangefinder cameras.Not done this, but have shot a whole 36 exposures of my other half saddling up and trying a new horse, oh the joy on her face, only to find the lens cap still firmly in place. Neither of us forgave Leica for that :hissy:
A few years ago I took a camera on a short day trip and found the battery warning blinking when I took the camera out for the first time and only got about five shots before it died . It was during my buy-on-eBay, try, sell-on-eBay camera testing phase so no spare battery.It happens to everybody I guess, it's just a matter of how long you notice it.
Although it's better than going somewhere to shoot and finding out you did not have a single memory card with you.