https://advrider.com/f/threads/cam-lobe-wear.1551611/ I have followed the thread since having ridden that evil 890. Just to remind myself why I have a Yamaha.
I had 2 E13's with the side knobs cracking. The MT21 on my Husky has seen dunes, Parklands and a ton on the highway. The D606 is good on dirt, doesn't wear well and sketchy on tar