Recently a user found his site banned from Google from setting his page rank cache too low. This post is just a notice to users to not change your pagerank cache to a low value.

I suggest that you leave it at 30, and if your site gets a lot of traffic you may even want to increase it to perhaps 45.

Page Rank updates approx every 3 months (there is NO set schedule) so updating more than every 30 days is a waste of resources and traffic anyways.