When I want to be technical I pull out the densitometer, make the curves, and file that in the back of
my head. Out in the field everything has to be intuitive. A few spotmeters readings, often under shifting
light conditions. No time for some calculator nonsense. No time to read Minor White's theories of religion or voodoo or whatever. No time to figure out what Ansel "really" meant. And yeah, I do have
the characteristic curve in my head and how I plan to use it, and not some cardboard zone zombie.
But then it's label the shot N, or N+, whatever.... good enough. Proper exposure, reasonably close development. If I'm doing something like color separations in the lab, then I get nitpicky. Developer temp within 1/10 degree on a thousand buck thermoregulator. Very precise monitoring of everything.
All that gets silly in the field. And I generally expose TMY-2 at 400 just like the box says, because it
has a nice steep toe and cleanly separates the shadows at least two "zones" below what Ansel taught,
or rather the stereotype of what he allegedly taught. But I don't think the Rochester people ever
particularly liked the guru "rocks and trees". I just do what works for me. I gave away all the AA how-to
books. Someone else can make the barefoot pilgrimage to that shrine.