Do you have the habit of highlighting important events in the wall calendar?  

My father in law has the habit of highlighting all important events of the year, immediately he gets a new year calendar. He is 80+ now , but I have been watching him since years doing this, Moreover as we follow our religion calendar which does not match with the English Calendar dates, he does this(in the English Calendar) so that no event is forgotten. Even otherwise I have seen people making a note of milkman's due, fees to be paid, electricity bills due date and so many other things highlighted and marked in the calendar to avoid forgetting those dates and things to be done.
So how many of you also have this habit?