From https://blogs.technet.microsoft.com/marj/2015/08/07/sharepoint-2010-workflows-best-practice-purge-workflow-history-list-items/, By default, Microsoft SharePoint Server 2010 runs a daily Workflow Auto Cleanup job to permanently delete workflow instances and related task entries that still exist 60 days after a workflow is completed or canceled.
Do you know what happens to Workflow with the Status Error Occurred? Are they also purged?
Christophe