The images above are shown as they started out, then after 10, 30 and 60 saves. The pixel damage is particularly obvious in large areas of nuanced gradient colour - chiefly the sky and water in these examples.
At this scale the artifacts weren't obvious for the first few saves. Seen at 100% or greater areas of the sky had become unacceptably degraded by as few as five saves, exhibiting the kind of level of damage seen at 10 saves in examples of this scale.
The damage is a result of the jpg's compressed nature. Keeping files in RAW, PSD or other non-compressed file formats will preserve quality and prevent this kind of distortion.
