I would say, like in the article small steps, having a clear goal for each session and consistency are crucial to shipping anything. I've been moonlighting on https://bullish.email for a couple of months following pretty much the rules outlined in the article, 1.5h Monday to Thurs sometimes Friday, and I just shipped a big update on my service. Time will tell if I'll lose motivation, but this is the first time I can manage a day job and a fully functional side project.