Journals are the incremental saves you find in the document timeline. They're useful to retain for a while after editing, in case a user needs to revert to an earlier version. However, these incremental edits can accumulate over time and increase the storage usage of your company.
If journaling is enabled, in the background journals that are older than 7 days are automatically removed based on the first checked-out entry for the file and the release entry in Timeline.
IMPORTANT:
The cleanup tool may not delete all the journal entries between the checked-out entry and the release entry in Timeline.
If the co-authoring session is running for a long time, say more than 30 days, then the cleanup tool may not find the first checked-out entry. This in turn may cause the tool to check for an intermediate checked-out entry in Timeline and remove the journals between this checked-out entry and the release entry in Timeline.