Like I said in answer to a similar question somewhere else in this thread, I rarely actually need to use this. But there have been times when it's come in handy

Like I said in answer to a similar question somewhere else in this thread, I rarely actually need to use this. But there have been times when it's come in handy, such as when I'm away from my computer and someone calls me on the phone to ask if I want to meet them for lunch on the 13th. I rarely remember my appointments by day of the month, but I do usually remember them by day of the week, i.e. I think "the 13th... (two seconds of mental math)... that's a Thursday. Right, I already made plans to have lunch with John Smith on Thursday next week." And then I can tell them "Sorry, I'm busy on the 13th, but I think I'm free on the 14th, let me check." And then I switch over to the calendar app, verify the 14th is free, and switch back to the phone app to confirm that I can meet them on Friday the 14th. That's how I end up using this most often. (And "most often" is still just every couple of months, mind). I still need to use the calendar app to record my appointments, but it sometimes lets me give people a "no, I'm busy that day, how about (other day)?" response with less of a conversational pause. So like you, I don't find it all that useful, but it still is nice to have from time to time. And I also just find it fun sometimes to know that the 13th of the month = Thursday without having to look anything up.