It uses a totally different method of selecting tracks, if you want tracks from one folder play more often than from another, you can use build the rotation like this:
(Track List) Folder 1
(Track List) Folder 2
(Track List) Folder 2
Here, tracks from "Folder 1" will be selected 33% of times (1/3), and from "Folder 2" 67% of times (2/3).
(Track List) Folder 1
(Track List) Folder 2
(Track List) Folder 2
Here, tracks from "Folder 1" will be selected 33% of times (1/3), and from "Folder 2" 67% of times (2/3).