What's in a Calendar?

I am of mixed feelings about teaching calendar. It is so repetitive and boring (to me) and the little students (pre-kindergartens, kindergartens and grade ones) take so long to do it. All these grades do calendar, or at least all that I have seen. But I wonder about the value, especially when 'research' shows if you do it later on in their lives, like when they are 7, they get it in about a week, instead of maybe a whole year.
Last year though, when I came into this class. Nobody knew anything about a calendar. Not how many days were in a week, not the days of the week, not the months, not even what the hell it was and what you would use it for. These were students ranging in grades from pre-kindergarten to 3 and aged from 4 to 10. And NOBODY knew a darn thing about a friggin calendar. Seeing this as being important (can you meet me for a job interview on Wednesday? yeah sure, uh ...) I immediately set about to remedy that. Well, the way I know how are 'baby' but I made them sing songs and learn the calendar. After doing the calendar everyday from anywhere to 20 to 40 minutes, by February they had finally gotten it. By february. Yes, I am not joking. I am not even talking about the kindergarteners and grade ones. Only the grade 2 and 3's got it by this time. I don't know who did the research showing that it takes 7 year olds only a week to learn the calendar system, but they didn't try it out on these kids. Yes, put these kids, average kids that they are, in your research so that WE CAN TEACH CALENDAR EVERY YEAR ALL YEAR LONG UNTIL HIGH SCHOOL, or something like that.