I can share only some unscientific observation. Few weeks ago, I tested SB-24 stand-by mode indoors with freshly charged 2000 mAh AA batteries.. I left it for almost 2 weeks, with occasional flashing at 1/16 intensity. Then I measured voltage of the batteries and all of them were at 1.3 V, so more than half-charged I would say. I concluded that this is more than satisfying performance. Of course, in cold outdoors conditions, the battery life would be certainly decreased. But I hope such wide community of camera trappers has some more valuable data to share with us