In brief: the geographic long tail. 15% of most peoples time is spent in places that they are in less than 1% of their time. People sometimes ask me why I want to start logging my GPS data, even if only privately – it's for this sort of stuff – to work out whether or not I can better optimise my personal possibility jelly. (And if I lost you there, then I suggest you google the term.) I'd like to better track what I'm doing with this 15%, and see if I can't grab some hours back.