Keith, how do you meter those exposures, or have you gotten to a point through trial & error where you just know where it needs to be?

I had the idea of taking an incident reading at the baseboard using the ISO of the panchro film, and using the exposure time at f/1.0.

I intend to do just what you've described in the future and any way to minimize film wasting would be good (for me at least... )