Les, I think you're worrying unnecessarily. Azamara have changed the wording on the website since their original communication to us to remove the ambiguity around 'days' versus 'hours' for precisely the reason you articulate. If you are embarking on Tuesday, a LFT from any time on Monday (or Tuesday) would be acceptable to Az. Ivi, in post #203 confirms the same after speaking to her TA.
However, I'm hoping Az will remove this particular requirement before our cruise in June. If not, we will be taking the test at the airport before we fly out the day before embarkation as per my recommendation to you. Even if I were wrong (which I'm not), the worst that would happen is that we would have to fork out again for Az's high-priced test at the pier. Not great I accept but not a showstopper. Plus, I don't have happy memories of the testers at Lisbon trying to push the swab through my brain and out the top of my skull when we took the free test before our November Az cruise!