The first 'flat' replacements were done at 13,000 miles in 2014 by dealer I bought it from, I didn't see how bad they were. These failed again 10,000 miles later in 2016 and photos are from then - even cam noses were screwed up. I rollered it buying the bits myself.
But story is they fail off edge of a cliff at any time and it's hard to notice it until the wear is so bad that the tappet clearances go to ratsh*t & you can throw entire set of feeler gauges in the gaps....and still it rides fine if slightly louder than normal so danger is they could wear down until the edges break off in big chunks - then you really are completely fuc*ed. Hence Pete et al struggling with 'it's fine'