I won't leave a dog unattended no more than half a day. A cat is a different story. For example...my cat...she doesn't care if I'm coming or going. I've gone days w/o seeing her coming out of her hole. She's a loner of sorts.
When I was a kid...we had to go out of town all day & came home LATE at night (can't remember where we went). Anyways...we had 4 Labs that we 'thought' would be ok.
NOT
It was apprx 18 hours we were gone & the neighbor checked in on them in the afternoon (fed & took out). They were probably just sitting there for about 6-8 hours unattended....got bored....& ripped up the kitchen floor, chewed half of the door to the basement, got over the barrier we put up & ate about half of my toys that I had in my toy box...chewed the leg off the rocking chair.....ate a few pair of shoes....(there's more...but you get the point).
On a side note which was funny....they didn't pee or shit in the house....go figure.