Thepemn has two quests, each with a short timeout. You can do any combination of them (5 of one, 3 of one and 2 of the other, etc). Because of the timeout, you can't just go there with a full backpack and instana-grind, but you can come back a while later.
For the tier 1 quests, the timeout to doing the same quest is 30 min. For the tier 2 quests, it's 2 hours.
Once you have completed 5 tier 1 quests, the tier 2 quests will also be offered (the tier 1 will still be there but don't count towards unlocking the next tier)
I like the system, but if they hadn't posted spoilers in the publish notes, I'm not sure I would have ever discovered it ... it's not intuitive that there's more than meets the eye.