A short discussion on the workings of this template is here: [1]
This code sets a rotation of any length. (mod x) where x = length
{{#switch:{{#expr:({{CURRENTDOW}}+{{CURRENTWEEK}}*7) mod 7}}
Currently the code used just sets a weekly rotation:
{{#switch:{{CURRENTDOW}}
The following code would set a monthly rotation
{{#switch:{{CURRENTDAY}}