Built in shaders - FX?

So, on this page (down to the graph with the cars):

it shows an FX color and a texture with a lot of white. Which seems to be replaced by the FX color. So this is a nice way I think to maybe reuse the same texture with different colors, without tinting the whole thing, like in case coding of material color. However, I’m not sure it would perform better than say creating several separate textures, since this is a FX shader. So I’m confused on this.

Is my understanding of that shader correct?
Is this better to use than several textures?

There’s no such thing as an “FX” shader - the example workflow on that doc page is simply meant to demonstrate how you can create different materials that share the same common shader and base texture, by combining it with different additional textures (which here have been described as “FX”).

So it’s not “better than” several textures, because that’s exactly what it is.