I’ll intellectually/emotionally/physically hard as answers. For me its either 12 hours straight “punching tubes” on a very large scotch marine firetube boiler at the beginning of my career or Easter around a decade ago when I was working with troubled teens and had to engage in 5 separate protective holds in one 16 hour double shift. The former was all physical and the latter was a combination of emotional and physical.
Yeah 24 hour stretches are no joke, mostly because of the driving at the end (for me at least). My standard shifts are 12s and I pick up a double every so often. Granted, I’m doing the same shit the whole time and most days it’s not very physical.