Yes, unfortunately I couldn't get my hands on the Adams' Bible, but I do use "Zone VI Workshop" by Fred Picker who describes the Adams' Zone System quite well I think. Apart from the time development control (mainly used in black and white processing), he explains in details how one has to control the shadows and highlight placement onto the characteristic curves, much more than the mid-range gray itself, in order to obtain a satisfying tone distribution in the final image. As in painting, an artistic approach cannot be summed up by placing a single tone on the curves. But don't get me wrong, I am not trying to obtain actual images. I'm involved in the development of an educational software, and so my purpose is merely to represent a simplified workflow in which a laboratory, getting a piece of negative film exposed following strictly lightmeters recommendations, calibrates a printer with the LAD, then tweaks the trimmer values to obtain a "correctly exposed" positive film. By "correctly exposed", I mean a 16% gray exposed on the negative (wherever it's been chosen to be placed on the curves) looks like a 16% gray to the audience, no less no more. All this is purely theoretical, there is absolutely no craft involved. It's a starting point to let people (and myself) play with, and eventually depart from to gain more specific knowledge about the real craft.
In this aspect, everything that you and Simon Wyss has written is a huge help to me, I'm extremely grateful to both of you. I would just need to be sure that the three diagrams I have showed are roughly representative of what I have just described, a very simplified workflow used by laboratories, lacking any kind of artistic considerations. If this approach complies enough with reality, I can start experimenting with the negative latitude, placement of the zones, consider the impact of color shift, grain, saturation, even processing (pushing, flashing, bleach bypass, ...).