There just too many variables not only in the shapes of a given riders bodily structure, but also a riders sensory experience. When we see a structural mage of the body, it's easy to assume that it's the same for everyone, but it's not.
There's no end to the variables to the interaction of a person and a saddle to distill it down to a number, or any other means of trying to quantify it. Just where does one begin to measure what can't measured ?
Trying a saddle is just like trying on clothes, you never know how it feel until you wear them awhile. How often have I bought some clothing after a favorable try on, only to find after some time, it constricts here, rubs there, the seams are in the wrong place, whatever. Saddles are no different. There are so many nuances to their shape and contact points, along with the riders shape and perception of contact, that it'll make your head spin just thinking of it. Saddle width alone doesn't mean anything more than what it is, the max width overall. Yeah so what, I don't ride on a number, I ride the saddle, the entire saddle !
The Cobb San Remo saddle I ride is an example of "trying it on". I have no idea how I found it. I knew Cobb made cranks and triathlon saddles, but not road saddles. I saw the San Remo, now called the Pro SR, and it is a "classic" racing shape, of which I was familiar with. I had no idea how it would actually feel. Now if I went by width alone, I would have never chosen it as it's 151mm wide. I overlooked that as just by looking at if from every angle and Cobbs additional measurements, I could see it was quite narrow where I needed to be, in the forward crotch bone area, ischial ramus as it's called. Not only in width, but also depth. In riding it the middle of the saddle has the right balance of flex and support. The nose is a very narrow 35mm, yes, that's more narrow than the rails. That's just what I needed however as I had never ridden a saddle with such a narrow nose. I also have a Ritchey Skyline saddle of similar overall shape, but the nose is not as narrow as the Cobb. I have not ridden it yet to know how it feels.