I have done my share of bad horses. I have seen this front leg strap in many horseshoeing books. I bothered you guys. My opinions about the leg strap are based on seeing one used, and the results. I will say that I never used one, after seeing the reaction, and a ruined knee on a potentially nice horse.
Much more time is consumed while using one also.
I deal with a problem like that in a quick, direct manner. Then I put the small rope under the lip, and snap the shank into the loop, making sure the lip-rope will stay in place, under the lip. Then I get under the horse, and every time the horse jerks the foot away , I pull very hard on the shank. I then get back under the horse, and repeat as neccessary. Soon the horse will learn that pulling the foot away has a price, and for me at least, quit resisting.