I agree with you about the narrative breakdown; it's clear that some of the devs wanted to try to keep a narrative thread going (like The Participants making a clear effort to refer back to Blanch, the participants and the test) while others didn't seem to make much effort to link at all (Day 11 seems to have zero connection to Organ of Eden).
I didn't really expect much from the length because I see it as a bit like the Haunted PS1 Demo Disc - more about concept and experience. 16 was one of my favourites, despite it's length, because I liked the concept of gathering herbs for a ritual: A longer game with expanded mechanics could be really cool. Likewise, Vale had really good atmosphere which made it far superior to Specimen 15 despite them being very similar in concept.