I can't answer your question on the basis of alt process but I may be able to answer your question on the basis of Azo.
In flat lighting the best that one can do is to plan on developing accordingly. I have been told that a SBR of 4.5 is a virtual impossibility so I take that as informed information. There is normally more local contrast then one realizes inherent in most scenes.
Film choice, EI, and developer all enter into the equation. The films that seem to be recognized as having the best expansion capabilities are Efke PL100, Tmax 400, and Ilford FP4. The developers that seem to have the greatest ability to expand contrast are ABC Pyro, and Pyrocat (of the staining developers).
Obviously if we are planning on a low SBR development procedure then the film will be shot at a higher EI. All of these factorws contribute to building density range in a negative.
The other thing that I think worth mentioning is that low contrast scenes are low contrast scenes. One does not take a foggy scene and expect to portray it as brightly lit and high contrast. That is where the long scale of the materials that you mention come into play...they are able to portray a palette of tonal variances unlike a silver enlarging paper.