Do you think if they would do it any other day, it would take less time? They are not just uploading offline patch to Steam. They have to upgrade whole online infrastructure, including store, configure new content and packages. Not everything can be prepared outside production environment. Also, you have an idea about time zones, right? So even if they started much earlier in the morning/night, there would be always someone who would like to play right now and complain. So again, what is your proposal?