NOPE.... you got to be fastened to the tree. I hook up before I start and don't undo it until I'm down.
A little story about your method from about 6 years ago. I bought a new composite arm stand that was made by the old Loggy factory at a show before they hit the stores. Brand new deal. (They took it off the market almost immediately after I bought it.) Anyway, I tried it in the yard a couple times and it seemed fine. I had owned climbers since the early 70s. The first trip to the woods was a 400 mile drive to the Adirondacks.
I walked in about 3/4 mile, put it on a tree and started up. I usually take a pretty big bite by putting the top part to my shoulders or doing a big pull up/push up pulling the bottom section with my feet. I was about 12 feet up when I took one of these bites. The top section broke dumping shoulders down on the bottom part which then broke leaving me hanging sort of upside down from a safety belt. Had I not been wearing the belt or had I been doing it your suggested way I would have ended up slamming into the ground from 12 or 14 feet head first. Had that happened you wouldn't have had any "Potty pictures" to adorn your screen.

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