How do you know where line typically breaks?
As you have surely read (ABOK/Ashely, e.g.),
that is precisely where the break is said to occur
–or even “slightly outside of the knot”!! (?!)
My take on the “outside” observation is of a double
mitigation, so to speak : (1) that the actual breakage
has been started within the knot, and it only seems
that “the break” occurred outside (I think that this is
partly what you argue, elsewhere); and (2) that the
broken area has been grievously weakened when
inside, and only later broke though it had moved
farther from that point.
My observations suggest that compression at a bend
plays a big role, with the inner / compressed fibres
being what break (first). In one case of slippery, HMPE,
the break seemed to come well inside, which I credit
to the material being able to deliver high tension
–w/o mitigation /“off-loading” via friction-- much
father along the SPart’s path (this seemed to be
past the SPart’s U-turn, of all things!).
And I think that (single strand!) spaghetti is not a good
model for normal cordage! Monofilament might suffer
some of the same problems for representing rope.