I get at least an extra day out of a charge when I turn off WiFi while I'm at work (I'm behind so many filters I don't want to go through that network anyway). When I get home I turn it right back on. So it does help, in my experience.
I just got my refurb a few days ago and it seems to have about 70% left when I plug it in for the night. Thats with ~15 min of talking and a lot of surf time.
I just checked my screen brightness and turned it way down. Thing was nearly hurting my eyes.