Let me start with film first, because it's not only analogous, but determines everything afterwards. And with today's VC papers, the cumulative question can develop a lot of layers fast. In other words, to make sense of it all, you need to think
of any specific film regimen as if a marriage to a specific paper, or even specific style of exposing a VC paper per se. It's
all relative. Old school terminology of paper "grades" gave a clue, but only with respect to a certain product line within a certain manufacturing brand. There never were absolute values.
H&D graphs are plotted visually for a reason. Sure, there are all sorts of match shortcuts people use to determine film speed, average contrast gamma, and so forth. But one really has to take in the entire cumulative curve, of better still, learn how to plot these for themselves, before the picture really hits home. Neither the Zon System nor any neo tweak thereof is a real substitute. You see, it's not just about whether a curve is long, short, or somewhere in between, but about the actual shape of that curve in relation to your own printing needs, and how that shape can potentially be altered or fine-tuned through selective exposure and development.
Still referring to film, even the definition of what constitutes the "straight line" portion of the curve can vary, and sadly, often according to over-optimistic marketing parameters. So you need to be aware of the character of the toe itself, and what shadow information within that to include or exclude from your film using the appropriate amount of exposure; and likewise, where the shoulder will appear, and how to control that if it's encountered.
Sounds complicated? No, it's not. Just learn the basics and practice. Exposure experiments combined with simple test strips from your favorite papers will tell you a hundred times more of practical value than all the math combined. But that does have it's place. I own two densitometers myself, and frequently use them. But they aren't essential. What is crucial is understanding how you want to distributes the tones in any given scene to please your own aesthetic taste. That applies, like I already hinted, to thinking of the film and paper in a combined sense, cause that's what you have when printing.
So did I answer your question? No. But if you have specific papers in mind, and specific films and developers too, perhaps I can. Otherwise, there are just too many variables to give a generic answer.
Sometimes there was a deliberate attempt to match film toe and straight line characteristics to a specific paper, like FP4 to MGIV. Or if you today compare MGWT to Bergger Neutral Tone VC, you'll discover that the toe of the latter drops off more steeply than MGWT, producing bolder but less detailed shadows unless one properly exposes the film for the differential - and Ilford/Harman happens to make both,even though they're marketed under different companies.
