Subledger Journals posting to GL in different Journal Batches

Summary

Trying to understand the logic for how subledger journals summarize when posted to GL

Content

A client recently ran create accounting (with "Final" accounting mode parameter) to post 1544 subledger journals to the GL.  All subledger journals had the same accounting date.  In the GL, 19 different journal batches were created. 

Can anyone provide clarity on what criteria is used to summarize the subledger journals when posting to the GL?

NOTE: Nothing was entered in the Journal Batch parameter when the team ran create accounting.

Thanks,
Kevin

Version

20D