Alas, for me that would probably be about 1:4000, but the good news is that would also be a good match for my running speed.
Your eyes have hung in there for quite some time. I knew it was the beginning of the end for me when comparing routes on a 1:15k blue course the other person said something like, "... and I took that trail there... " Well yes, that trail would have been a nice route, IF I HAD SEEN IT! Even standing still post race was difficult. The legs were still willing but my eyes, which have worn glasses since age 10, couldn't keep up. Alas, such as it is for most aging orienteers. You are lucky to be aging very slowly eyeball wise, and leg wise I might add. Broccoli pizza must be doing some good.
Perhaps I have been luckier than many; my (corrected) vision was really good still until about 1 1/2 to 2 years ago, but things have definitely gone downhill since then. I guess all the years of whisky, cocaine, womanizing, fighting down at the Buckhorn, and watching "Fox and Friends" have taken their toll. My doctor keeps telling me I really need to give up "Fox and Friends", but it's so hard.
Somewhat along the lines of your story, some years back at a race on a map I had made, I overheard someone complaining about some large unmapped rocks on one leg that had really thrown him off. I was curious to see what I had missed and where it was they were. It turned out they were mapped--he just couldn't see them on the map. It made you wonder if he could see *anything* on the map.
But as far as legs go, luck hasn't had much to do with it. I made the choice a long time ago that I wanted to stay fit, and I have put in the time and effort all along. There aren't any short cuts.
Health also requires luck. How fit do you suppose you'd be at this point if you had been laid low by some unfortunate affliction or accident, like volvulus or a bicycle crash?
Well there you have it. J-J says it's all a matter of luck.