On the settings page, a few things seem unnecessary from the screenshot and should be improved.
- The due date is either empty or set to the current time. It seems like it should default to now + 1 week similar to assignments
- There is a checkbox next to "and has a time limit" it seems like just putting any value other than 0h / 0m would trigger the time limit, remove this check box and maybe separate out this time limit box
- Late submissions seem fine, but I feel like this "Yes until" box should probably be empty forcing the user to enter a date. Ideally it would set it to whatever the due date is at the time if you went into here but it can't be before the due date.
It's just kind of confusing to set these settings and they're having some issues when setting extended time.