Can't find it - but I notice GS gives one verse of Ps 50, and then says et repetitur antiphona, pro opportunitate, post unum-quemque versiculum psalmi 50
Perhaps this is the discussion you're looking for, CGZ? It's not the topic of the thread, but you ask the question about lengthening the Asperges about 7 comments from the top and get some good responses.
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