One thing I've been doing recently is working with a Stouffer step wedge for working out development times and contrast with a couple of new films and papers. It really helps to be able to see the actual changes in contrast, exposure and development on one sheet of paper. A "normal" picture taken with the variables in contrast inherent in an image makes it more difficult to judge development times.
With the step wedge, all variables are able to be controlled and changes are easy to compare because there is no variation within the shot (like shadow values and highlights). All of this is done in a controlled manner which makes subtle changes easier to evaluate and understand.