Hadn't really though about it DieSse abd I suppose you're right. I've got my AVG set to automatically update but do tend to check the updates manually when I first switch on. I suppose the postings are a bit of a waste of time really but hadn't really thought about it.
Any anti-virus s/w is only effective if it has the latest virus definitions installed. This is the basic maxim of AV practices.
As AVG only auto updates once a day, if you don't check manually for updates, you can miss the very latest definitions that are available.
If, like today, several virus definition versions have been released, a system that only updates once a day would be vulnerable to the latest virus threats that are "doing the rounds". If you miss an auto-update "window", then your system would be running with definitions that aren't effective against the latest virus's. That's not a good scenario.
That's why I, and I assume other members, start threads about AVG updates. To let other members know there's an update available, so we can keep our AV s/w as up to date as possible, and be more pro-active in defending our systems.