Okay I toyed with prerequisites.
Say I want section I, to complete Module A before progressing to Module C, and section II to complete Module B before progressing to C
The issue is that if C is assigned to everyone there's no way to specify prerequisites for C by section so I tried specifying both A and B as prereqs.
As a student in section I, I see Module C having both A and B as prereqs, even though I cannot see B. But having A alone completed seems to let this student progress to C
I emphasize that the student in section did not complete B, but is allowed to progress to C on the basis of having done A.