--the friction build-up overwhelms it. 
That s the good news ! The friction build-up is sufficient to block the binder completely , 2 B sure !

We have to tighten the binder in more than one step, as I have already said for the other similar binders: First, we pull the proper end of the
"one way" mechanism, so that the first loop shrinks to the desired degree, and tensions the binder. Then, and only then, having the size of this first loop fixed by the "first line of defence", the one way mechanism, then we make sure the "blocking end" stays a little tensioned, ( so it remains parallel to the "blocked" end, and the mechanism does not fall apart ). How do we achieve this task ? By passing the tail through the second and third lines of defence, eliminating any slack rope that is left on the second loop.
It might look complex at first, but, after a little practice, it is not. We first have to master this
"one way" mechanism, get the "feeling" of how it blocks the slippage of the rope through the bight when we pull it by the one end, while it allows it when we pull it by the other end. ( We must only make sure that the two legs of the rope are parallel to each other, so we must always maintain a small tensile force on the "blocking" end as well.)