To me, it's two highly related, but slightly different disciplines:
1. Can I correlate what I see around me with what's on my map? (
map first terrain association)
2. Can I correlate what I see on my map with what's around me? (
terrain first terrain association)
Two sides of the same coin, really.
If I'm looking at my map trying to find something, I start with the map first and then look around me.
The other side of the coin occurs as I walk along. I continually look around me. If I see a peak, saddle, or other distinctive land form, I identify it on my map.
I find that identifying distinctive terrain features as I go keeps me constantly oriented. If I come upon the unexpected, I already have a good idea of where I am and am
less likely to get confused. Case in point, on trip in the Rockies a few years ago, my buddy was doing terrain association, map first. He came to a trail junction. There was only one trail junction on our route in that area, but he couldn't quite get things to add up and was a bit confused.
I on the other hand was doing terrain association, terrain first. I already knew approximately where we were based on terrain, and I figured it out in a split second: The trail had been re-routed, and the junction was no longer where it was shown on the map.
Both sides of the "coin" (map first, terrain first) have their place, but for continuously staying oriented, my money is on terrain first.
HJ