Hello! I heard Will ask you about the 1:12,500 map scale on Saturday, but I didn't hear your answer for why you chose that scale. I am curious...!
I figured/guessed that maybe a few people would come over and say some nice things in an attempt to soften me up before asking why I chose that scale. And it worked! Besides the people that did ask about the scale, there were a couple of other people that came over, said some nice things, but then couldn't quite get up the courage to ask about the map scale. They were probably the most fun, and, you know, it is such a touchy topic. ; )
That said, 1:12,500 is a nice compromise scale. Many people who have problems with 1:15,000 can manage 1:12,500 pretty well so long as there aren't large amounts of very fine detail. And in a good many terrains, 1:10,000 ends up being overkill (larger than necessary) with the downside that longer legs get tougher to see in their entirety.
And in this particular case, after doing the rough course design, I checked it against paper size, and saw it would fit fine on 8 1/2 x 11 paper at 1:12,500. If the course had proved to be a little bit too big, I would have adjusted it so it would have fit. If it had fit easily at 1:10,000, then I would have printed at that scale despite what I wrote above.
Ah, that all makes sense. :-)
Anders Nordberg often printed training courses at "one to A4" scale, which means the largest scale that would fit nicely on an A4 sheet. This was often 1:8000 but could also be other random figures. I think it's a perfectly rational method.
It's really rational if you have a whole bunch of A4 and nothing of anything else!