I don't think category #1 is exclusive to family, it could also apply to anyone you want to remember but is prone to fall off your contact list, like friends from high school, favorite authors (so you know when they publish a new book), local businesses, etc. Basically stuff where you want several months of activity artificially compressed into a digest that you can spend 5-15 minutes on once per quarter to keep up, rather than 1 minute every day (a total of 90 minutes per quarter).