In my native language, German, it's almost exclusively this word order, "Tag und Nacht". "Nacht und Tag" sounds weird to me.
It may mean what it literally says, both during the day and at night, or can be used in a more figurative way, conveying to something like "all the time" or "non-stop", often indicating that you'd want it to happen less frequently or that it normally would be less.
On Reverso context, I found several different translations to English: https://context.reverso.net/traduccion/ ... und nacht, with "day and night" having most results, followed by "night and day".
Looking at the examples, it seemed to me that "night and day" might be more common in that latter, figurative sense, but possibly this impression is wrong.
Thus, my question is: do you use "night and day" and "day and night" interchangeably, or is there a difference in meaning?
(I'm kind of undecided in which subforum this should go. The moderators might want to move it in case my choice was wrong.)