Sunday afternoon, I dropped by one such session at Panera Bread in Jenkintown, where eight writers sat at laptops, lost in their own imagined worlds.
Beth Parks Aronson, 48, a therapist, was at work, imagining her own demise. "My daughter is 30-something. My husband is dead. I am dying of ALS. I don't want to go in a nursing home. I want to die on a sailboat headed to Italy. Two hunky crewmen would help."
Her opening line: "Is that even legal?"
National Novel Writing Month - or NaNoWriMo - began in 1999 when Chris Baty, a San Francisco freelancer, e-mailed his friends, challenging them to spend the next 30 days on fiction.
"Quality is of no concern," he asserted. "Don't have an ending? Just stop writing at page 200 - real writers do it all the time! No plot? No worries! Some of the best novels of the past 20 years haven't had plots."
By concentrating on production, his theory goes, the creative pressure releases. And something good can always come from the act of writing.
Stars have emerged from the process, such as Sara Gruen, who began Water for Elephants one such November. More typical is Arthur Fleschner, 65, who by day manages an office for an Episcopal social services agency in Philadelphia.
"I write during [NaNoWriMo] because it is the only writing contest you can win if you are like me, absent of a great idea, can't spell, and wouldn't recognize a dangling participle if it was highlighted in red in a grammar book," he says. "Most years, I have only a vague idea of what my story will be about. So I am as surprised by what happens in my novels as I am in the books I buy. Three years ago, I did a murder mystery and didn't have a clue who did it until the last three days of November."
Cassie Panek is 28, a former frame-shop employee who puts her English degree from Arcadia to work in a blog about the television shows The Walking Dead and American Horror Story.
Three Novembers ago, she spent the month on a vampire novel. The next year, she produced what she calls "an urban slice of life - Sex and The City with Mohawks and not so many shoes." Last year, she tried an airship adventure.
Her current book is about a reluctant Louisiana debutante who finds her life changed by the advent of the Civil War.
She's thinking of cutting her first 20,000 words because she found her plot late, but the good news is she's already hit the magic number. Easier to do, she says, when not employed.
Aronson said raising a 5-year-old daughter while seeing patients left little time for writing. Then there's the issue of her husband, Dan.
"He's not thrilled that he's dead in my book. I told him it's a plot device. He has to be dead so I can sail to Italy. Besides, he doesn't even like to sail."
Contact Daniel Rubin at 215-854-5917, email@example.com, or follow on Twitter @danielrubin or Facebook at http://ph.ly/DanRubin