Having a design requirement that would be easily solved if scheduler could initiate based on the presence of work items in a target work queue.
Example:
Fire schedule every 15 minutes IF( [Workqueue1].ContainsWorkItems(>0) )
This would allow a scheduler to check every 15 minutes for the target work queue ('Workqueue1') has a work item greater than zero.
Some additions to this could include filtering on tags/status/ attempts or other work queue related data points.