Everything depends on the dog itself.
I'm assuming we're discussing getting them out to go to the bathroom
My previous two girls could not really go more than about 8 hours as adults before they had to get outside, or they would go to the bathroom in the house.
Finn has been able to go for up to 12 hours without relieving himself. Even as a 10 week old he just didn't need to get out that much. I've never left Finn alone for 12 hours. I just know this from observation. I make sure that Finn gets out as much as possible during the day, and I take him out as the last thing I do at night. He's never woken me up at night to go out, not even as an 10 week old puppy,so I know he can go 8 hours easily, but I don't ever push it.
Me personally, I think 8 hours is about the maximum extent to expect a dog to go without relieving itself. Anything over 6 and I don't blame the dog. Yes, some can go longer, but that's a lot of time.