It all seems like it should be obvious, yet too often people tend to compartmentalize the calibration of their materials and processes. You get your hands on a densitometer and the next thing you know you're developing roll after roll trying to home in on a 0.1 for EI and 1.2 for Zone VIII and the right curve shape, without making actual test photographs and prints along the way. After all that work you find out you're not making the negatives you need.