Why 4:00 am?
The first version of Penciletin started its day at midnight because that’s just how most calendars work. But that was awkward. Once upon a time, I worked the overnight shift. If I ever went to bed before 3:00 am would just mess up my sleep schedule and make me useless the next day. So I would go to the 24 hour grocery store at 2:00 am.
There is always going to be a time that is difficult for the user interface. I could have kept it at midnight so that it looks like Apple’s calendar, but I moved it to 4:00 am for the people like me working graveyard.