break it so fast it's not funny. Short term duration of a password means people won't put in a lot of effort to remember it, so it's either very weak and easy to remember or written down. I've lost track of the number of people I know who have little books they carry around with account names and strong passwords written in them so they can remember them and not have to mess them up again. If they lose the book they lose everything.

A few very strong passwords that you can remember and change only every year or two or three, and you're much better off as it would take a great hacker longer than a few years to break a very strong password that's ten or more digits long. So you're safe with a long life password. but as I said before, you're better off with a number of passwords you remember and use them for different levels of security for the sites you visit.