On the one hand, I agree with the author - my definition is the same as theirs. On the other hand, I have moved to a country where everyone else uses a differen

On the one hand, I agree with the author - my definition is the same as theirs. On the other hand, I have moved to a country where everyone else uses a different system (it differs on whether "next friday" is in 6 days if we're talking during saturday). Are they wrong? Is all of this arbitrary? I think that learning to navigate these differences part of being a better communicator and a better person.