Schoology had a feature were you could offer formative quizzes to students so they could attempt a quiz multiple times without any teacher interaction. Schoology would keep old attempts and notify a teacher when another attempt was made. OnCampus does not keep student attempts on quizes and requires a teacher to reset the assignment.
For those of us using blended learning (taking homework out of the classroom), this is very important. Ideally, I would like unlimited attempts throughout a grading period. I would also like to be able to see that attempts are outstanding and need to be reviewed by me.