I love your final sentence: I also keep at writing because I'm starting to see some signs that I'm getting better. That seems to be the important thing: to do good work and to be a good writer.

(As to hours per day, I'm in the middle of writing an article on which I worked for five hours in the wee hours today and will probably work about that much again beginning in a few minutes. Most of this work was/is online research. I'm not fast, so my total of hours per day may be high when compared with many other Medium writers.)