I play with Yonex EZONE 98s, strung with a full bed of Solinco Hyper-G 16L between 47-51, depending on my mood and the season. I string my own rackets and have been monitoring the exacts on breaking/dead habits for the past few months. I pop a string every 4-6 hours, but typically toward the 4-4.5 hours mark. If they don't break (rare), they die after about 8 hours.
Of course, as many people have said above, this is largely contingent on a bunch of factors (type of ball you hit, level, tension, how often you play, etc). For my case, I'm a 5.5-6.0 (ex-college recruit), play 3-4 times a week, and hit with a ton of topspin. For years I played with Luxilon ALU Power, but was breaking it at the same frequency mentioned above, so I moved over to Solinco Hyper-G, which is a fraction of the price and for me, it plays really well and is super comfortable. Worth trying out if you haven't already. I hate that it's neon green, but doesn't deter me from using it, hah.
Maybe an odd opinion, but I think that Hyper-G plays at its peak toward the 3-4 hour mark of play, which for me, is when it is about to break.