As per current mechanism , If new version release then we must need to put live store into maintenance mode or need to do it into staging and need to upgrade version first and then test whole site and if any issue occurred with current code then need to fix it and after all of stuff doing we able to move latest code into live site.
It all taking minimum 1 hrs if user's have very high speed server to complete this process.
If magento have auto update version feature like auto update browser version then it will more safely way to choose magento than other framework.