In review stages, a batch is checked out (materialized) based on the group ranking and the sort order defined for that batch. So when using the Next Available option, documents will be pulled from the next-highest-ranking group with un-reviewed documents, in the defined sort order.
Furthermore, within a given group, we give precedence in the following order:
- Any checked-in batches that have zero documents reviewed
- New batches
- Any checked-in batches that have been partially reviewed