Just to help anyone else who may be reading this thread:
In the Add Rover window, the How often option refers to how often the show, webisode, podcast, etc, is set to air. The settings for how often to refresh the search results are in Preferences -> Timing. Here you can define the Timing categories and set how often that category should refresh. These categories are the different colors you see in the Rovers list. If you want to see the color code, just show the Sidebar (F7), and open the Timing expander. Here's a quick explanation of the timing categories:
Finished: The rover is finished because you downloaded something from it.
Waiting: For recurring rovers (daily/weekly), the next episode isn't out yet.
New - Very Late: Describes how long it's been since a result was expected or since the Rover was added. These are the timings that you can define in Preferences -> Timing.