What is the meaning of 'six-week course'?
It is not uncommon for visiting scholars/professors to give a short high-intensity course during their period of visit. These have little relation to the usual/normal university semester/summer schedule since they are (1) tied to the limited visit of somebody, and (2) aimed at people not burdened by classes on the normal schedule (not undergraduates or early grad students in the US).
I have seen these as a full day once a week, half days several times a week - whatever can fit into the schedules of the visitor and the pool of people who want to take the course.