Robert Boice, a psychological professor, spent his career studying the writing habits of fellow academics.
His conclusion was that the most productive and successful among them made writing a smaller part of their daily routine than others. They wrote in brief daily sessions – sometimes as short as 10 minutes and never longer than 4 hours – and religiously took weekends off.
They cultivated the patience to tolerate the fact that they probably wouldn’t be producing very much on any given day, with the result that they produced much more over the long term.
(H/T – Oliver Burkeman’s Four Thousand Weeks)