I just recently found the technique, and have only tested at ground level. When crossed, I slipped a little and then it caught, parallel it just kept sliding. The crossed ropes might catch on the step when falling.
When on a linesmen’s, if you need to lean in, force your hips back to keep it tensioned. Pressing the two strands together also maintains tension for leaning in, to the point you can hold both in one hand to allow use of the other. To advance the rope, lean in a little and whip it up with both hands, not with the fingers like a tether.
Aiders seem to be the wrong choice, as your feet are forced into the tree, or sweeping out from under. Circus performers climb up the side of their long ladder type aiders to keep their center of gravity closer to the aider. With a linesmen’s I can walk up a 5 step etrier in just a few seconds with no slack to deal with.
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