Event rewarding should scale with how much time (considering an event that do not start because it’s predecessor in the event chain isn’t often completed) and/or tries since last successful end. It should include drop rates by monsters spawned by/related with this event. That way people would go for different event chains and regions. Since grinding is discouraged but some recipes needs hard to find materials, this approach would give more dynamic to end game, while also spreading it across different maps.