To further John's point:
Let's take a database of several hundred styles. Yes, you still have to 1.,choose a song,2 decide what style to use,3 What changes you want 4,where to put them.

That is one song,so you then want to narrow the songs down to a list of the ones to be played on a gig,from the database,to a set list. And, let's assume you have to make these changes quickly in performance.