camp
Setting up camp last summer, I met a young smaller framed woman who used both an alpha direct layer and a Timmermade down puffy.  Lots of warmth considering she could combine it all with her Borah bivy sack and her quilt if need be (going to assume she had alpha pants and sleeping socks with her visible set up).  Individual warmth preferences, hanging out vs diving right into the quilt/sleeping bag, etc..  We had a common table stopping at “Hikertown” during the unseasonal chill, and, despite the cold wind when we went through, I was doing ok with a Airmesh (“Octa”) hoodie under a Montbell Tachyon until that sun set.  Could’ve used an added puffy vest myself.
At a certain number of long sleeves layers, the Michelin Man effect takes over.
performance minimalism
Another idea may be toughness.  I took a first version of the Ghost Whisperer, with water-resistant 800 down, on a trip and the shell survived a slip on a slimy sidewalk with slight cheese grater surface (then again, ripped a hole in the sleeve when I brushed it against regular drywall).  Wonder how much toughness could be imparted for little weight gain?  (down here there’s always spiny or thorny plants waiting to snag fabric … remember Mountain Hardwear had a now defunct baselayer that would handle even desert spines).