I don't think all of these exercises are perfect, however, I think they are good and I enjoyed the process of each one of them. I think I tried different things in every one and I liked the results. "La practica hace al maestro" translation? : "practice makes the teacher" does it make sense? anyway, I believe that to be true... I still have to do a lot of practice but I think these exercises show a pretty good progress after many tries and frustrations!