This is a superb, no-nonsense article that tells the truth about writing a novel alongside a full-time job. I did it between 2004 and 2020. I have three traditionally published novels, ten self-published novels, and another ten novels sitting on the shelf in varying states of disrepair (varying from first draft to fully polished and ready for publication).
I did all of this alongside a very demanding full-time job. People ask how I had the time. My response? People make time for what is important to them. I made my writing a priority. I did many of the things you describe here - ie wrote during lunch breaks, wrote in the evenings, wrote at weekends, etc. I had a daily goal of 1,000 words, and 2,000 words per day at weekends. It became a routine I ate, slept, and breathed. Sometimes I would take time off - a week here, or a month there (typically December), but I stuck to that routine rigidly.
Since leaving the aforementioned full-time job, my writing routines have evolved (I'm now on Medium, for instance), but they remain important routines.
Thanks again for this article. :)