Then it puzzles me why 3 cards are dead. I suppose they do not optimize their shuffle to pick a song from an already read flash page, so many shuffles -> many read disturbs -> page refresh (move to a fresh page, mark old as garbage) -> garbage collection -> repeat 1000x -> card death. Maybe, this is also amplified by bad drivers and bad cards, as you've said. Sadly, none of these are open source. sigh...