Writing is not a job with hours or even deadlines, unless you count the self imposed one. Because of that I have always been fascinated by the routines and daily schedules of other writers and artists. There is so much self discipline involved in being a dedicated writer. Some of my friends write best in bars, others measure their writing time by cups of tea, everyone has different rituals or habits. I generally get my best creative work done in the morning and then spend my afternoons editing and doing other assorted work.
I find the habits of famous writers I admire as fascinating as those of my friends. Winston Churchill wrote many large volumes of text. He did most of his wok in concentrated focused periods, often at night. However unlike most writers, he dictated the vast majority of his later work to a typist.
Auden did not believe in writing on a full stomach. He did the bulk of his writing in the morning after a breakfast of coffee, orange juice, and a cigarette. He also tended to keep his lunches light, as he often wrote in the afternoon as well.
Raymond Chandler put around four hours a day aside for writing. In those four hours he did not have to write, but he did not allow himself to do anything else.
Last year I read a fascinating article, that I highly recommend called Self-Control Techniques of Famous Novelists by Irving Wallace. I have actually not read much by Irving Wallace besides the article, but I found the details of his routine, fascinating. When writing his first book at 19, he kept a work chart, a tradition he has maintained since then. The charts record the date he started each chapter and the date he finished it, and the number of pages written within that period. By the time he reached his fifth book, he also recorded how many pages he wrote a day. A page from the chart is included in the article.
The article also includes a great deal of other writers routines. Trollope and Hemingway also kept charts of their progress. Balzac, Flaubert, Conrad, and Hemingway, averaged at least six hours of concentrated writing a day.
Some people associate writing with inspiration, but often that comes with a great deal of hard work and self discipline.