When I took a class on machine applique, I was using the right leg for everything. The instructor said that I should learn to use the left foot on the pedal and it was easier than I thought it would be. Mainly, because when doing machine applique, you are sewing a lot slower and it just makes things easier for me. On the first machine that I ever sewed on, ( an industrial one ) the " gas pedal " was where we now have the knee lift and even sewing with a knee lift was something that required a lot of practice and re-programming of the mind.