In a nutshell, there are no shortcuts. Many of the great musicians have had a training in a certain style (classical, jazz, etc). What they did was take a little bit from everything they've learned to create their own style. Very few musicians (and I mean very few) sat down with basic music theory if any and said, "I like how this sounds, maybe I'll stick with this." Even then, it was their ear that picked up a certain style and they attached to it. So it all comes from a training in a style. I can almost guarantee, JT and Rodney East have a few choices of styles while they are playing and they are just picking from their mental library. The key is you have to put something in your mental library to pull it out.