Actually, the septum, or the thick senew fiber layer but not hard like a ligament, is part of the penile reinforced strength from accidental damage. Think of it like a hot air balloon cable that holds things together without letting the balloon from popping, bursting, or warping.
This is why we say to bundled the stretches. When bundling the stretches, what we're stressing is this layer of fibrous senew, or the septum, and the outer layers on both side (technically it's only one thinner layer) called the tunica. But if you do not stress these fibrous materials during your lengthening process, you cannot make your penis longer The tunica restricts you from getting larger. This is why the efforts for lengthening is a hell lot longer for length than girth.