Rotate study group leadership and topics fairly.
Rotating leadership fairly means dividing the meeting count by members rather than the topic count, since a leader may cover several topics in one sitting. Meetings needed is topics divided by topics per meeting rounded up, and dividing by meetings per week converts it to weeks. Both the leadership turns and the preparation share are reported because a rotation can be fair on one and unfair on the other.
Schedule
Meetings required = ceiling(topics / topics per meeting); weeks = meetings / meetings per week
Fair rotation
Lead turns per member = meetings / members; topics per member = topics / members
Usually yes — leading a topic works because preparing to teach it forces deeper processing. Separating the two roles removes most of the benefit for the leader.
Rotate the remainder across cycles so the same people are not always leading the extra session. Tracking cumulative turns rather than per-cycle turns keeps it fair over a term.