Hmm… Ok. Let’s now see what the update holds…
For AntiVir, the threats are quickly injected in database, even if the update is done once a day.
For Avast!.. the threats are injected in database between 8 - 15 days after detected (i.e.: just scan files at VirusTotal). So… perhaps the updates are done frequently. But they don’t get the last protection… because the main Avast! database isn’t update yet. A few examples: Bagle, Virut, Vundo (security toolbar variant), MSN & WL messenger worms (I’m helper in french security forums for a year now, and never seen avast! founing this kind worms).