Good point; I wonder how many people take that approach. I personally tend to log out of Gmail after I read my email, which signs me out of my Google Account fairly regularly. But maybe that's an unusual use pattern.
I always log out of my Gmail account when I am done reading my e-mail, as well. Until recently, when I've come across several people who stay logged in all the time, I thought that was the 'normal' use pattern. Then again, I'm old and "back in the day" you always logged out of an application/system when you were done.