The thing is: you want to finish this thing in one go, because enemies don't get harder and 'the further' you go the more drop. And once you begin run, you can't start another quests (unless you stop the run, which is not advisable, because of above), so it's pretty much few hours of farming this shit and ending event in one day preferably. At least you get about 1.5m gems from this, so you won't have to worry about gem quests for a while.