I have had guitars that break strings more then others, I have had periods of time when I break break strings more then others - there seems to be differnet reasons strings break m0ore often then others - the way you play (hard picking) will make a differnece - the strings you choose (some break more then others) - the weather (I ceratinly break more strings wehn it's hot and humid then any other time) - and the way you tune (many players use multiple tunings or even stay with alternate tunings and either of the conditions can add to the wear on the life of the string).

On my Larrivee, I played it for two years before I broke a string (and I play hard). Since then I've broken a few more, but only in the very humid air. I've yet to break a banjo string (and I retune my 5th string a lot, so I'm expecting it). But on other guitars, especially one on which I regularly use an alternate tuning, I break them more often.