I assume fillippone is a merit source, so there's no reason for him to ever hoard merits. Don't know if it's the same with all the merit sources, but my sMerits get replenished very quickly--way faster than it was when I first got tapped to be a source.
Nothing has changed - source merits get back to you 30 days after spending them. You allocation has probably increased since those early days so it seems faster.
As for hoarding, one can accumulate personal merits while spending all source merits, which could allow (completely hypothetically of course) to spend some ungodly amount in one month but in the long run that doesn't change anything.