Perhaps they could have daily schedules that change to a new one if you correctly intervene. Like, say, there's a farmer trying to get to market across bandit territory. Each day he sets out, is attacked, and retreats. This repeats daily (because that boy is resolute) for as long as you don't intervene, either because you haven't discovered the scenario or you got distracted by a cucco six days running. Then you intervene, bandits are no more. Now the farmer has a new cycle, popping off to market daily to sell his wares (maybe making some cool new item available to you). But he has a new issue - he's trying to get someone to sell him a site in town so he doesn't have to make the journey every day. Each day he goes to see this character and try to convince them to sell, but nothing doing - until you intervene, and so on. Basically each cycle except the very last has a failure state. Five different cycles would be a pretty involving side quest for one NPC, and there's the excitement of seeing what will happen tomorrow once you successfully intervene.
You could have multiple NPCs across the world, each following an initial daily cycle until you nudge them onto the next, like a train switching tracks. If you were truly diabolically clever, you could have all of them intertwine, or come together once everyone is on their final cycle to reveal some ultimate reward or dungeon, like an episode of Seinfeld tying together seemingly disparate threads.