Is not the important thing to feel the torque required rapidly go through the roof as the wood is nipped up and the collar is suddenly holding everything apart? The precise torque required to compress the wood may vary a bit due to different wood, damaged threads, etc, but you can sure feel the sudden change to steel on steel at which point I stop. I find that, occasionally, I can tell if a collar is too long or short by the feel.
Ridolpho