How often does PS plus update?

Yeah, what ^ said. Guaranteed monthly update with a new PSN title (next month there's two), a PS1 title, 2 minis, a dynamic theme and a couple of avatars plus whatever else Sony feels like handing out. Then they also occasionally update throughout the month with themes, DLC, games or when applicable, betas.

First is was every week, then became every other week, now they just randomly bleed out stuff throughout the month.