I went through and counted up all my Eneloops I think I have. 384. Yeah, way too many, and I might have missed some in a device or two I've forgot about. About half of them I've never used yet. Of all the rest (including some from 2006), none have failed me yet. One of the 2006 cells is showing its age. A few more have reduced capacity because I cooked them in a light that gets too hot. I have reverse-charged a couple of them (drained flat in a multi-cell device, with a cell getting a small negative voltage), but they show no ill effects of it.
I generally take good care of them. I usually charge them slow, on chargers that terminate reliably and don't trickle-charge. I think the most any of them have been cycled is probably 300 or 400 times, but probably not even that much. So, the biggest issue most of them face is age. But so far, they're holding up very well. Way better than any other brand I've had in the past (but I've only bought Eneloops for the past 10 years).
I usually charge at least 16 cells per day, so they get a lot of use. But that use is spread out over a lot of cells.