Well after the first vanished quest I found out it was two weeks but the first quest I had in stormheim I didn't know how long I had so I worked at it slowly. In fact I had read nothing about archaeology in Legion so I didn't even realize the quest would ever go away I thought it was just something you had to complete to progress much like the other profession quests.
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God I hope so. Slowly leveling my alt and I'm not looking forward to grinding that rep out for a 2nd time.