I've noticed recently that my SD disks are failing at a much higher rate than DD. However, on average, my SD disks are older than my DS disks.
Is there something unique about using SD disks on the Apple II that results in greater failure rate, or is it more likely just that the disks are a couple of years older? They are all stored under the same conditions.
My failure rate for DD disks has risen to about 1.5%/yr, while SD are at 19%. (By no means a rigorous, scientific test, but I do keep basic stats.)