like bootlaggger says, depends on how often you play, and how hard you play, strumming hard or plucking.
But I would reckon after a year whether it got played or not is long enough for any guitar to have the same strings on.
I play daily, even if for one song or 5 minutes, but usually at least 3 songs a day up to 60 ( depending if i have company in and how much whisky i have drank <img src="images/smiley_icons/icon_lol.gif" border=0 alt="Laughing"> )
I change my strings about once every 2 or 3 months, which means I need to change mine again, thnk it has been 4 months.
Also, if you snap a string, you are better replacing the 6 of them rather than just one.
Ken
ye get some that are cut out for the job and others just get by from pretending