me_irl

We didn't do it regularly, but if my old group got into the metaphysics of how specific spells work a single combat session could take 8-12 hours. There was more than one combat scenario that took so long for us to get through that they took two sessions.

There was a reason that we really, really tried diplomacy first. Hell we managed to make alliances between the humans and orcs, and the dwarves and kobolds. Murder hobos we were not. We even had homes.

Edit: the stupidest part about that is that if we weren't having fun figuring out creative ways to deal with encounters, either we would have wiped/TPK'd or mopped the floor with almost every encounter. Our DM was constantly throwing the hardest stuff he thought we might stand a chance against and we consistently ended most combat within 2-3 turns.

That DM eventually enlisted other DMs to try to design challenging encounters for us. Turns out that when your core PCs decided to be a Wizard/Dweomersmith, a Cleric/Loremaster, and a Psionic Monk of Quivering Palm, and two of them took Leadership, you really need a CR of about 10+ levels above that party to slow them down.

I haven't actually done 8, but I have played for 6 hours before. Our games move really slowly, definitely more role-playing than roll-playing, so it's a lot of narrative and story-telling. Doesn't help that the DM is very into D&D enough to run multiple campaigns.

Yeah it'd definitely be a marathon though. But my point was that even if it is too many hours (e.g. for practical reasons), I think it would be unfair to say that it's too many hours in the sense of "you need other hobbies."