I tie commercially. My visce jaws are set so that the hook is roughly between my Adam's Apple and lower jaw and I get as close as I can to the hook while keeping my back straight. This means I buitl me bench so that I have room to really pull my chair in. I use tons of light. I take a break between every dozen to pratice my long-distance focusing. I tie 5-8 dozen per day right now...will ramp back down to 1 or 2 dozen in my "off-time."

I think it's better ergonomically to have the vice high so your back and neck remain as straight as possible. But you will need to "suffer" a bti until your traps and shoulders develop enough to support your arms.