There comes a time...

I have always wondered why people, when writing autobiographies, seem to write in terms of months passing, years and of the changes that they face then. For me, it has always seemed that so much emotion can be lived in a day, so much drama and change and mood swings, that it is insufficient to only paint one's changes, particularly in moods (eg. he was depressed, she was jubilant, they were purposeful) only in months and years and not days and minutes and sun-hours. Because a life can be lived in a day, and months can follow on end of nothing.