Example: If you have not yet reached exit number 5 is the "next exit" referring to exit 5 or exit 6? "This exit" is clearly exit 5.
Similar to the "next Tuesday" question Which day does "next Tuesday" refer to?
Learn English – What highway exit does “Next Exit” refer to
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Best Answer
I would take "next exit" to always mean the first exit you come to after this point - in other words, junction 5 in your example.
The only exception is if someone made the distinction really clear, by saying something like "not this exit but next exit". But that would only make sense if you were already passing, or very close to passing, the current exit.