Not each week, but at my university, they had enough focus on the science part that most semester long solo projects were semester long and solo only in name. S

Not each week, but at my university, they had enough focus on the science part that most semester long solo projects were semester long and solo only in name. Students were assigned some component or incremental stage of some larger project spanning years and multiple PhDs, not some assignment for assignment's sake. That certainly did not make them perfect learning environments because students were left to their own in how they solve cooperation (postgrads running those macro projects might be considered PO, but not technical leads, and just as clueless as the rest) but the "pass on to the next each week" approach would have exactly the same gaps.