I know what you're saying, Ron, but I think there might be a small chance that it is confusing in the context of Kevin's questions.
% gelatin is not the first thing that comes to mind when thinking about grain sizes and size distribution curves. The rule of thumb about speed of precipitation (the first few minutes of making an emulsion when the salts and the silver are brought together, a.k.a. "addition") is "fast pptn gives higher contrast". True, as far as it goes, but it is based on the assumption that the emulsion maker is using the minimum possible amount of precipitation gelatin. It might help to look at the 'why' of that.
In the first moments of addition, the grains formed are smaller than microscopic, but they immediately start growing. Some dissolve and their materials go into larger crystals. Some just join together outright. The character of an emulsion is set by a number of factors, but primarily by how long the ripening goes on (the time given the emulsion after precipitation to grow crystals). During all this, gelatin is keeping things in suspension. Usually, it's just enough to keep things in suspension. Because, the higher the percent gelatin the chemicals are swimming in, (i.e. the thicker the soup) the harder it is for the crystals to mix it up and grow. The result is that the emulsion ends up with more small crystals and fewer crystals of a mixture of sizes. It is the mixture of sizes that is the primary mechanism of contrast. Slow precipitation is just another way to allow the small crystals to grow.
Between precipitation/addition time and % gelatin, along with the initial concentration of the halide and the silver, we have almost an infinite number of options for making an emulsion. I think this makes things easier, not harder, to get started cooking. If you start with a decent recipe and play around, while learning just a few facts, you simply can't go wrong.