I began my post-retirement writing career researching the habits of famous writers. I wanted to know how easily or difficult they found the skill. Much like any other skill I discovered certain practices, behaviors or personal characteristics contributed to, or impacted their writing. Among them is a daily writing routine. In my process I discovered an author I did not know and his view of writing habits. Graham Green number-of-words per day is a common strategy, but not one I have internalized.
I often take a workshop where we were assigned weekly prompts to write 500 words. It is a useful weekly practice, but my struggle to meet a consistent daily goal continues. Occasionally I write every day, especially when I am editing, though most writers would not regard editing as writing as it may not include any new narrative. At other times, I write hundreds of words a day over many days.
I can see the disadvantage of these inconsistencies but I wonder if each of us doesn't simply fall into the habit that seem to work best for her? You can find Graham Green's notion for the writing habit here: https://www.openculture.com/2020/05/write-only-500-words-per-day-and-publish-50-books-graham-greenes-writing-method.html
What's your writing habit? What do you do when you fall off track?