i've also been very skeptical of such 'loose' ties;
but have seen this on plenty of trucks and find the Cirque du Soleil's tent technicians reference very enlightening.
In both these we have possible rain swelling of nylon and wind vibrations testing the theories!
But, i also manufacture and use this knot differently..
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Arborist call any such 3/1 pull config a Zrig, any pulley system etc. a jig, in our world Zrig can have adjustable Prusic instead of fixed position eye.
Have used this system for tiedowns, pulling stuck vehicles free from mud, lifting engines, pulling down massive trees some leaning in wrong direction and had to guide against their lean, pulling stuck transmission etc. Also as a 3/1 pulling another or even a 5/1(=15/1), pre-tighten another larger line used for rigging for less drop /impact on line when takes load etc. Have also pulled Trucker's Hitch with a 2 ton truck, to lift limbs from over screened enclosures over pools, skylights etc., where we couldn't lower and no one could get a crane in. So used existing tree architecture as fixed boom and 2 ton truck pulling into 3/1 rig like this to make large lifts. i always said the last direction to drop something is up!
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one of Xarax's Noose w/HH's comes closest to what i found for my purposes and theories:
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A problem of the (two) loops based upon the slipped overhand knot, is the very sharp first curves of the free ends, and the ends of the bight. An easy way to address this problem, is to form a nipping loop above the slipped overhand knot, and to pass the bight through it. Besides the fact that now the first curves are smoother, this possibility might be considered as an advantage of tying a slipped overhand loop - because it gives us the flexibility to beef it up that way, if, at any time after we have tied the simpler loop in the first place, we would decide that we should better need a more stable and stronger loop for our trucker s hitch.
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i had switched from Butterfly to this somewhere along the way, as found Bfly sometimes hard to untie after pulling w/truck, and not best angle of pull on eye.
i find this to be also simply a Bfly with unlinked rings;
another viewable mechanic is can see as a Zeppelin with one side reversed to meet/ form eye.
For me this is easier like Zepp untie, than Bfly, less picking the lock.
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Bfly is very good knot use for many things, even jug sling for me etc. but think eye should pull perpendicular if at all.
i first did this as an upgrade to noose instead of Bfly in Trucker's and also pinata hanging, simply thru the HH around eye as fix w/o teardown.
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Eventually evolved to fortifying the highest loading side; i guess as Xarax suggests.
Now simply a fig.10 noose w/HH construction; but still i think Bfly and Zepp forms also discernible.
Unties easier than Bfly i think, easier to adjust eye, more correct proper pull angle on eye.
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Going up over a load and back down with 3/1 is a 6/1 potential less the frictions, angles.
i don't look at friction as foe, but rather buffer.
Harder to take line 'purchase' thru friction buffer, but then once you have purchase friction buffer also helps hold it.
So, if send momentary peak force thru line, that can't really hold, might trick more purchase that frictions holds for you.
2 ways to send peak force 'wave' thru line is to impact bodyWeight or snatch hard with effort.
The faster the better; 2 matching trucks , 1 that weighs half as much going 2x as fast has 2x the force, so hit into jig hard and confidentally!
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Also, sharply bending line to sweat or swig more purchase, then let frictions help hold.
Should then look at jig side might be 2x tension of offside, so stretch and vibrate line to equalize line on both sides of load, and pull jig again!
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IF pull end of jig, have 3xEffort potential up to bodyweight hang. Can add 3xEffort to that by pulling other anchor.
But if put that same pull inside system at rite point get 4xEffort +3xBodyWeight, can impact with either/both.
Impact hits can come at same time to hit hardest against load, or sequentially to get something moving and keep moving etc.
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If really want to tighten for tiedown, make ropes iron bar tight by above methods. Then make shallow bends. The tighter the line, the more line resists bend; the more leveraged return in line tension!
