It might be my slight experience in modeling that made me think of it, or just the reflexive instinct of a C++ programmer to minimize every bit of memory usage, but I totally removed everything I could whilst still keeping the shape.
NOTE: If any new student comes across and wants to try this at this stage, rather than “Remove Doubles”, use the “Merge” option directly above it (shortcut Alt+M on Windows).
Hint: “At First” or “At Last” are your go to answer, depending on the order you select the vertices to merge. 