Thank you all for your advice and kindness!
Even though I know you don't necessarily say that out of kindness (I hope), knowing that you think I've improved, even if I can't realize it makes me very happy!! I already train several times a week to make random shapes to work on the accuracy of my lines but I will try to do it every day. I absolutely see what you mean Drunkenelf ! I started to learn art seriously again at the beginning of the month and I researched so much that I had no time for practice, and I couldn't remember anything. However, I don't think learning one thing at a time is an effective method. I understand your point of view and you are certainly right but for me there is so much to know in art that, especially if you are self-taught, you cannot afford to perform in one area before moving on to the next. Mastering a single field in art can take years and we always have to learn and as I imagine all the artists in the world I have time constraints to respect to become better otherwise I will unfortunately not be able to live from my passion. I also do cubism but not a lot, I will try to practice more but I don't think I can do 45min before each drawing session, otherwise I will have to shorten my practice time even more. Thanks for trying to motivate me Dark Intent Arts but I don't think I'm really discouraged, I was just a little (a lot) scared that I'm suddenly stopped to improve. I am someone who is used to trusting the process without really asking questions. Given my current level, I don't have the time anyway.
Thank you very much for your advice !! If I understand correctly you advise me to redraw over the drawings I made today trying to use all my shoulder and make 10min of 2min sketches? I'm sorry if that's not what you wanted to tell me but I don't speak English, I use translation software to understand and I can't find the right translation of your advice in my language, that doesn't mean anything.