Office 365 documents auto check in time can be measured in hours
Office 365 CheckOut Manager gives you access to all checked out documents in SharePoint Online libraries. With this simple tool, you can set reminders and auto check in time for checked out documents. So you have no need to remember about all checked out files in your Office 365 and can avoid conflicts in SharePoint environment when multiple users might want to edit checked out content.
The recently added feature allows you to set the notifications period and auto check in period in days or in hours.
Type 0 in the "Notification Period (day)" field or in the "CheckIn Period (day)" field to open the fields with values in hours.
You can learn more about all abilities of Virto Office 365 CheckOut Manager and download its trial version as well.