I see - so the scheduler health check is actually checking:
1.  what buckets are allocated, and 
2.  not just whether there is some old event that should have been process long ago, but instead which bucket are unhealthy (have really old events).

Is that right?  In that case, would it make sense to not just have a list of old events, but a dictionary of oldest event per bucket?  I know the buckets are listed in the health check, but in between when the cassandra queries were made and when they return, the buckets might get repartitioned.