The game uses checkpoints, no?
So what does 'Save & Exit' really mean?

Exactly as it means. Save game (progress) & then exit game. It's an actual save. It won't start you back at a checkpoint.

Um, okay, but it does not seem to do a thing as every time I reload the game I am at a dock or the standing stones.
Not the location I "Save and Exit"ed.

Yep. You are right. My bad. I've only started playing the game (and playing it on and off, with too long of a break inbetween to have noticed before). It starts me back at the last check point (or beginning of an area, or somewhere "safe?"). The 'save' in 'save and exit' is useless? Oh well, I guess I should have checked before posting.

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