Your batman study is super good : )
I have never given feedback before as I feel like I don't know enough or felt like I was overstepping haha. But I thought I would share something I learned from doing the daily pen control exercises, in case it is helpful.
I completed the exercises a lot of times and in hindsight I found that I had wasted a lot of time with the straight line exercises by putting them down too quickly without thinking beforehand (also because I found this exercise the most boring I tried to get through it as quick as possible meaning I wasn't focused 
). I used to draw the lines quickly without setting a clear start and end point—either on paper with dots or even just mentally. Because of that, I now find I still overshoot when drawing straight lines. I was only focused on making the lines straight, not on controlling where they started or ended and put them down on the paper too quickly.
I wish when I was doing them I had set an initial start and end point for the line on the paper (with a dot) or just in my mind as I think this would have greatly helped my pen control. I dont know if you are approaching the exercise in a similar way but I think it could be helpful to give it a go if you try the exercise again. Just a thought in case you revisit the exercise!
