so i found out this week that the weekly WG quest "slay them all" can be done daily.
you simply have to have somebody share the quest with you after you have already completed it and it will allow you to do it again.
EDIT: this also works for victory and the siege vehicle quests. tested today.
EDIT: alright so i figured out how this works. it does have to do with the fact that quests have IDs just like instances and raids. where blizzard /failed is that when you are attacking and defending the same quest has a different ID. so if you are attacking one day then you come out the next, you can accept the same quests from the defending quest givers. so you can do the weekly's twice a week. hope this helps