How is Skin Texture Created?
This is more a matter of curiosity than anything else, but I have to wonder how professional skin textures are made. After all, I've studied the various details of skin textures used with the various models, and there is a whole host of details that must be addresses during the process of making such a texture. Cracked skin, imperfections, placement of various anatomical details, and more. And perhaps I'm being lazy, but I would have to imagine that the creation of such a texture from scratch would be a labor-intensive endeavor.
So how exactly is it done? Is there a special software that makes creating skin easier? Brushes? Photo references? How is it done?

Comments
I personally use high res photo references of real life models and paint each skin texture from scratch using the photos I have.
There are other ways such as using merchant resources or products that are designed for this such as the Skin Builder in store right now.
As for specific software I think any 3D painting software will do. And you need a 2D image editor as well Photoshop/Gimp.
If you look at sites like Artstation, a lot of the bespoke skins are kickstarted using textures from vendors like texturing.xyz
A very popular skin texturing resource is https://www.3d.sk/ Some of their resources are also sold at Rendo where you can also find tutorials for creating realistic skins in the marketplace although I'm not sure how recent those are.
And if you go to youtube and search for 3d skin texturing, you will get an insane amount of video tutorials using everything from Blacksmith3d to Mari.