In the activity completion section of the settings for Workshop, there are 2 settings for condition-based completion (ie, under "show activity as complete when conditions are met"). One setting is "student must view activity to complete it" and the other is "student must receive a grade to complete it". The second one is more useful, but it is problematic as the following can happen (and does happen frequently in my experience):
1. A student submits their work and assesses all the submissions allocated to them, but does not receive any assessments. The activity is not marked as complete for them (as they have not received a grade), even though they have taken part fully in the submission and assessment phases.
2. A student submits their work and receives assessments from others, but does not assess submissions allocated to them. The activity is marked as complete for them (as they have received a grade), even though they have not taken part in the assessment phase.
So students can be unfairly penalized for the negligence of their peers, or unfairly benefit even if they are negligent!
I think there should be an additional completion criterion: "student must complete at least these many assessments to complete this activity" followed by a box to put in a number.
This way, only those students who take part in the submission phase and the assessment phase will see the completion check mark.