Retention Policies and OneNote Notebooks

Does anyone have any enterprise best practices concerning how to manage/maintain OneNote notebooks when your organization requires retention policies in OneDrive and SPO?

I have a situation where notebooks started to be deleted from users' OneDrives (x) days after they were created. We found that the modified date doesn't change when a user modifies a section or page of the notebook, only when a notebook's property has been changed. For the time being, our workaround is to update the notebook's name, but I can't suggest that to 6,000+ users as a long-term fix.