What's you calendar organization scheme?

I have my personal calendar and work calendar. When I'm in school I also have a class calendar and a homework calendar (all day events that start and end corresponding to when assignments are given and due). I also have access to my sister's personal and work calendars because we live together and share a car. she has the same permissions for my calendars with view settings so she doesn't see my work meeting names and vice versa.

I use Google Calendar so tasks are their own thing. I do use them for specific tasks that seed to be performed at a certain time or day, but don't require a full event such as taking out the trash or submitting an invoice.

It depends. I'm fine with the default public holidays calendar, but you may have different needs.