I’m moving to Seattle in a month and am finally going to be able to ice climb on a semi-regular basis. I’m stoked but also a little anxious because ice climbing is my weakest area as far as experience goes. Perusing the ‘net I found this nifty video of Petzl doing field tests of ice screw strength. My takeaways are that the threads of the ice screw are where the strength is at and ice screws fail not because they slide out but because they get torqued and the ice above them flakes off. Taking the next logical step, for the strongest ice screw placement I would want to minimize torquing by placing them at a slight downward angle (the direction of a fall) which would put as much force as possible on the threads of the ice screw.