I have a Phenom with well over 400 games, and it still hooks great! At about the 300-game mark, I did the Ebonite Hook-Again treatment and a resurface, and the ball still hooks and carries very well. Sure there's a loss in performance compared to out of the box, but it's expected, and the performance loss is very minimal.
I did leave a 7-10 with it recently while shooting on a sport shot, but c'mon now, the shot was hard and the oil was pretty heavy...that doesn't mean the ball isn't working anymore. Chris Barnes and Mike Devaney left 7-10's on TV and their pin carry wasn't awesome; that doesn't mean the Inferno and Big Bully are bad balls whose coverstocks don't hold up - the condition was maybe just tougher and/or heavier.
I also have a Rule with over 100 games and an Animal with over 70 games, and these balls still react awesome! The balls obviously don't hook as much as the day I first tried them, but that's expected. On the same sport shot as I left the 7-10 with my Phenom, my Animal wasn't picking up its roll as hard and pin-action wasn't the greatest. At another house on a heavy-oil THS, the Animal just murders the pins. Some balls just match up better to different lanes and oil patterns.
These are just my experiences and thoughts; not balls are made 100% equal, so there may be some discrepancies, but I don't believe that balls lose reaction THAT fast.
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-Dino