Microtonality mid-scale is a distinct (though related) topic to overall range of the film. It will differ with
different films, different development regimens, differernt print papers and developers, and even different camera lenses. To make sense of it you'd first need to learn to plot these step readings onto a curve using a desitometer, assuming you understand how to interpret these things in the first place. The Zone system is only moderately useful in this respect. It's pretty generalized. Eventually you just have to home in on a specific film, developer, and paper to learn the working dialect. Othewise, buy a
serious textbook on sensitometry - which will itself have little practical value unless you understand
what you want your film to do !