I know this has been posted several times before. Lots of posts about it, and lots of [status-complete].
This image shows a default recent activity duration of 8 minutes and 49 seconds. I had not clicked any page in the SE network for 7ish hours. (unless I sleep-surfed the net.)
This image shows a duration of 6 seconds!! I'd been browsing SO and other sites in the network, but hadn't clicked a page on SO in several minutes (though I can't verify the times on this one).
Is it something in the way I'm browsing the SE network? Could it be that I have the Stack Overflow Notifier extension and that is conflicting? I did disable it for awhile but still had issues with the duration.