I ran across an advice from a professional novel writer.
He talks about the triangle as a requirement to jack up your writing speed: knowledge, time, and enthusiasm. I don’t get it much for enthusiasm, but I fully agree on knowledge and time. By knowledge, he means to prepare bullet points of what you are going to write spending 5 minutes before you start writing about something. For time, he emphasizes on tracking the output performance in terms of word count. In his case, writing during afternoon at a coffee shop without internet works best, so he rescheduled everything to write at that time frame and viciously protected it. These are good advice, though I don’t expect me writing 10k words a day. In my case, I need to actually “do” some research–data processing, running regressions, and literature review. Nevertheless, I think I can do better than the current word count, 1.5k per day if spend the whole day.