my work print doesn't show the meter readings. I only had 2 stops difference. Everything was coated in a fine red dust. The walls had been white washed, but they were even sort of pinkish. To get more of a tonal range that is why I added the 20% more to the development time. On plus minus development, I go by how many stops of seperation there are. for 4 to 5 I do normal. for anything 3 to 2 I do +1. anything from 6 to 8 I would do -1. This is my system. If the readings come out more than the above, then I have to decide if I want more or less contrast for the sceneand do +2 or -2 development. That is when my brain hurts.