I'm not familiar with the BTZS but I've done a lot of awful, boring testing over the years and I honestly think that the pay off in my pictorial prints is visible and well worth the effort. It's not fun but there are so many things that affect the contrast and density of the negative and finally the print. Camera, Lenses, shutters, meter, enlarger, metering technique, processing techniques, film, developer, paper choice even your local water, to mention just a few.
The only way to take into account all of the dozens of variables in the unique, personal choices of equipment, materials and techniques that are made between first evaluating the scene to be photographed and the final dry print is through tests that account for all of these variables.
As far as the ZS is concerned. I don't shoot much sheet film but having a solid normal process to start from, I can make expansions and contractions based on general lighting conditions, for instance if I pop a couple rolls on a flat, cloudy day I can bump the contrast.
-Neal