When I used to work in a 24/7 environment I would quip that "it's not tomorrow until the morning crew takes over." In a lot of practical situations I think it's easier for people to think about the early morning hours as being late the previous day. It tends to match shifts and reporting cycles better.
It's not tomorrow until I've been to sleep. It's not the morning until I've had a cup of coffee. Time is incredibly subjective. Clocks need to agree, but nomenclature does not.
I had a software project where I thought I could infer which shift was working from the time (because shift-related metrics were really important). I learned very quickly that shift and time, though related, are really separate data points.
