Which version of avast are you running, v8.0 or v2014?
v2014 is on a different vps update cycle than previous versions.
If you are using v2014 you should be receiving continuous streaming updates.
Continuous streaming updates keeps the user protected while reducing the need
for regular vps updates. 8)
edit…
No, your avast is not missing anything this is proven by the fact that you are receiving the continuous streaming updates.
As I mentioned, you are very much being protected. Don’t get too hung up on vps versions.