2 to 6 hours is an unrealistic amount of practice time for anyone who isn’t paid to practice. Even many college students studying fine art don’t get that much practice on a truly daily basis.
Make sure you’re putting in 15 minutes of focused practice every single day. By focused practice, I mean always have a specific goal in mind before you put pencil to paper, as detailed in this article:
https://line-of-action.com/focused-practice-an-exercise-for-real-improvement-in-33-days/
15 minutes per day will at least keep your brain focused on the task of making new and better connections regarding these skills.
Then, add in a few days in the week when you will do longer practices; 30 minutes, an hour, two hours, whatever is realistic.
Unfortunately, your links don’t work for me so I can’t give more specific feedback, but I wanted to provide some comfort that meaningful progress IS possible without needing to devote your entire life to improving.