Question

Is there a way of defining auto enrollment off a certain number of failures. For instance, once you fail 3 campaigns, you get auto enrolled?

Answer

There is not an automated way to change the number of failures required to auto-enroll in training.  However, you can run a report and export those users that failed x number of campaigns.  You can then re-import those users with an additional column/property to differentiate those users and use that new property to create the next assignment.
 

See Auto-Enrollment Conditions  for additional information.