I think it was Kult’s Taroticum that had a section of the adventure where the PCs were travelling between dimensions, and if they had a mishap they’d be stuck for a literal eternity in solid bedrock, but as they were still in some sort of half-astral form they were completely unharmed. In a conscious sort of stasis, I suppose – conscious, because that’s how they’d suffer for their mistakes. If they were to somehow return to the “real” world, no more than minutes would have gone by. I suppose this was intended as a cue for the GM to Deus Ex Machina them out of there at some point after they’d suffered enough, but I didn’t really pick up on that.

Player: “An eternity, huh?”
Me: “Yup. You feel bored… and soon enough the boredom gives way to an itching… and the itching gives way to torturous pain…”
Player, interrupting: “Okay, I’m going to start swimming.”
Me: “Um, it’s rock. Bedrock. You can’t swim through it!”
Player: “It’s cool. I have an eternity to work on it, learn exactly how to do it. And I can’t hurt myself doing it, need no nourishment and have no expenses, and got nothing else to do.”
Me: “Oh, um, okay… you spend some time… like, a year, maybe… and then a fingertip starts to wiggle a little.”
Player: “Cool cool. I’ll just keep doing this until I can swim my way out of here.”
Me: “Uh. Okay. Hrm.” ::starts turning to another player::
Player: “Oh, hang on.” ::picks up the book, turns to the Experience and Learning chapter:: “Says here that I can improve my skills if I spend enough time on it.”
Me: “Shit.”
Player: ::marks 15 (max) under AGL, STR, CON, ‘Swim’ on his character sheet::

Moral of story: if you’re going to make an experience system only contingent on subjective time spent with no abstract currency, don’t create a cosmology where characters get stuck in time bubbles on the reg. I wonder how many Kult characters come out with max values in ‘Interrogation’ and ‘Survival’ when reborn into a new body after being tortured by a Nepharite for an ‘eternity’.