The justification is the text of the quest itself.
Example: Save Halsin, he got captured by goblins. He's either rotting in a cage, or goblin stew.
2 days later you go to goblin camp and find him rotting in a cage, save him and off you go.
However, player 2 waits 4 days and goes and finds some fat goblins talking about how tasty druid stew is.
The timers indicate a different outcome which varies based on the context of the quest.
Yes, i agree, but it would have to be like that for every quest and it gets even more difficult when you embrace quests that are not self-contained, but i think that's some way along the road ;D. trained neural networks for character archetypes initialized for every npc when you load up the game and the things they see will influence what they do. thatwould be the dream.