Suggestions: How often do they update?

I just can't remember how often TiVo suggestions update. My wifi effectively updates the guide and whatever daily, but I don't see the suggestions update.

I frequently go to the suggestions to thumbs up and thumbs down, so the data base will learn to predict some shows I don't think of.

However, it seems the same ones have been there for a few days, and the list just gets shorter as the days roll by.