So there are no workarounds for it to update more frequent like registry hacks or something?
Ok, lets explain this the other way around...
AVIRA Free checks for updates only every 24 hours. Settings are locked to end user.
AVG Free checks for updates only every 24 hours or when connecting to internet. Settings are mostly locked to end user.
MSE checks for updates only every 24 hours or before doing a scheduled scan (which is also set to every 24 hours by default). No settings available.
avast! Free checks for updates every 4 hours and when connecting to internet. It can be set to 2 hour (120 minutes) check intervals through settings.
So even if you don't fiddle with avast! update settings it's still checking for new updates 6 times more frequent than any competitor product or if you set it to 120 minutes manually, 12 times more frequent. I could hardly ask for more really. If you want more frequent update checks you should check avast! pro and IS editions.