Another reason all the ones I have posted have the twist as close to the loop as possible is that it's a more direct application of force to the plug. The more circular the loop, the better it applies tension to the plug. Once you put that sharp bend in the wrench it becomes a place for energy to collect, and like a kink in a hose reduces water flow, then bend reduces the amount of tension that is acting directly on the plug. That's not based on text book theory so much as first hand experience. I have a mountain of trial and error tension wrenches in a drawer in my work area to prove it and some look very similar to what you have spun.
The final reason for the closed loop is that it fits on belt clip with my keyring, so it's portable and accessable. It's the first bottom of the keyway wrench I reach for not only because it's one of my favourite, but also because it's right there on my belt.
One thing I forgot to mention in the tutorial is that if you choose to bend one, make sure you coil it backwards. That is to say if you want the arm of the wrench to point to the right in a keyway with the pins at the top, bend it as though you wanted it pointing left. Then bend the wrench tip under the arm so you have a tight coil with no gaps. Does that make sense? You want the wrench tip next to the plug face, but bend it as though you wanted the loop in the way of the wrench tip, then reverse it.
I have a U wrench myself, as well as a double ended loop wrench. Great job again on forming the curve so smooth. I don't find much use for either because they simply won't fit in a tool case. I suppose you could patent the designs and start production, but that's not exactly in the spirit of DIY and I can think of better ways to go bankrupt.
Mine involves supplementing a young girls college tuition with dollar bills. Incidentally I also have a dual sided tensioner that works as a money clip. If I ever had any bills to put in it, then I wouldn't have so much free time to bend tension wrenches. -Tooly
), but seeing all those shiny looped tensioners makes me think of some abstract art yard 
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