The other (the first two pictures) look like they as well will bite too hard and therefore make this knot harder to release for the use in ascending a rope or backing up a rappel, grip and slide scenarios, etc. The x'd crossings being like the related parts of a constrictor, locking whatever is underneath very hard
That was the purpose of the double parallel or the double crossed ( X ) neck... that is, to bite hard into the standing ends, and prevent any subsequent slippage of them through it. Do not let the (superficial) name suggest we are looking for any sort of a climbing hitch here, that would need to be released easily, when "used in ascending a rope or backing up a rappel, grip and slide scenarios, etc." Perhaps the name is really misleading, and we should describe those knots only as "multi-coiled Bull hitches". It was just a hard gripping hitch around a pole that I was looking for here, without any concern for easiness of tying or untying, possibility of sliding alongside the pole or tensioned rope, etc.
I believe that the climbing hitches is an altogether other world, strange and unknown to me... The functions that climbing hitches have to fulfill, are many, and much more complex than what we require of a common hitch. I would never dare to suggest any climbing friction hitch to climbers, or pretend I have discovered a way to "improve" the Prusik...
I have also to point out that it is a very different thing to tie those hitches around a pole, than to tie them around a tensioned rope. I am talking here about the fact that a segment of the pole can not revolve in relation to another, as it can happen in a rope. When the standing ends pull the ends of the coil tube to one direction, say, clockwise, while the transverse, bight element pull the other ends to the other, counter-clockwise, a rope at the core of the coil can adjust itself and follow the local twisting, by twisting itself, while a pole can not. A rope can never resist to torsion forces as much as a pole ! So the final geometry, and the tension forces inside the different segments of the coil tube, would be different at the hitch-around-a-rope, than at the hitch-around-a pole. In short, I expect those hitches to be more effective when wrapped around poles, than when wrapped around ropes.
