Does the blow-in settle?

No, not Havelock Wool. But, to be clear, traditional blown-in fibers are inherently weak, brittle and have a tendency to absorb moisture/water like a sponge. Under their own mass they will settle. In an attempt to prevent settling, these fibers are installed at high densities. Fortunately, the wool fiber has several built-in (natural) designs and chemistry to help prevent slumping. #1 It’s shaped like a spring. #2 When in the presence of vapor or water the individual fibers begin to move and also help fight slumping. It’s the reason you don’t see any moldy sheep.