I dont weld for hours on end at home, but when I worked as a welder it was 10 hour days and at least 8 of it was with hood down. I worked mostly in weld out yards and fab shop so it was hood down all the time. I used a shade 10 lens as most of the weld out yards were outside open air. If I worked inside on fab table tacking and running beads. I used a 9. Never had a problem with burned eyes. I used a penlight to check my gaskets every day after I changed clear lenses to make sure everything was seated right. 99% of the time when someone gets burned eyes it is from leaks around the lens gasket or from backreflections from shiny objects behind them. I have seen pipeline welders weld all day long with #8 lens and not get eyes burned. Most folks dont run more than 150 amps welding unless you are working in a shipyard welding 7/32 or 1/4" Jetrod then you could need an 11 outside or 12inside. I have never seen a #14 lens. I doubt you could see the arc of a 3/32 or 1/8 rod with a #14 as you can barely see it with a 12.