Comment by Arch485

I feel like days are a non-issue; they would just start at different times (UTC) in different territories. This wouldn't make things any more complicated than they already are (currently, if I want to talk to someone in Australia, I have to look up what time it is in Australia and infer the day of the week from that, if necessary. If everything is under UTC, I know what "time" it is, but I still have to look up what day it is).

Most of the issues time zones cause are not "day of the week" related anyways (at least in my experience), so I think having to figure out what day of the week it is somewhere else wouldn't be a common problem anyways.