When I look at the calendar, I want to be able to quickly see what needs to be done. If I can't differentiate between what's open and what's closed than it's harder to plan my day - I know I can go into the calendar search screen to pull up open or closed items - but seeing it on a calendar helps those who are visual learners. I use google calendar for my personal family calendar and when I complete a task I change the color to purple so whenever I look at my calendar, anything that is purple means it is done.
How often would you use this request?
Every day - maybe even a few times a day perhaps