im a bit curious about this as well, i bought the 43mm extra long hammered fenders from Velo-orange some time ago and for the fork crown where the indentation was the hole that was pre-drilled didnt match with the one under 'under' the fork crown, so that when using that hole you can see maybe 3/8 of an inch sticking forward of the fork crown. I thought it was a bit silly that I would have to drill a second hole for it to line up correctly, but I assumed it was because of the variance between different bikes.

Its especially visible in my case because I am using canti-brakes