I update manually because of my bad experiences with all antivirus. if the server is not found, there is no message showing that error, and the program keeps trying to connect, leaving the Internet connection unusable. But in fact, i did not try with avast.
Man, you're using avast and not any other antivirus
avast checks if there is an available connection each 40 seconds.
If there isn't, wait more 40 seconds to check. Checking does not take more than one second and, of course, does not use the Internet band.
If there is a connection, check for an update. If there is not any new file to download, wait 4 hours to start checking again. If there is an available update, start it and install it. Again, wait 4 hours to check the next time.
Some of this settings could be configurated different, I posted the default values of the avast4.ini file.
The updates are incremental. This is the wiser method of updating I have ever seen in a antivirus
