The title of the Jacqueline Susann novel and film "Once Is Not Enough" derives from a conversation Susann had with her old friend, comedian Joe E. Lewis, on his deathbed. Trying to perk up his spirits, she supposedly said, "Come on, Joe. Didn't you always say 'you only go around once, but if you play your cards right, once is enough'? Lewis responded, "I was wrong, Jackie. Once is not enough."
The character of novelist Tom Colt (David Janssen) was based on Norman Mailer. The award that Colt had won was the Pulitzer Prize. In real life, Mailer won the Pulitzer Prize for Literature for "The Armies of the Night" in 1969. Mailer won a second Pulitzer Prize after the film was made, in 1980 for "The Executioner's Song".
The movie, and the novel it was based on, was famous for containing fictionalized portraits of real people, including heiress Barbara Hutton (Alexis Smith), "Cosmopolitan" editor and author Helen Gurley Brown (Brenda Vaccaro), reclusive actress Greta Garbo (Melina Mercouri), and author Norman Mailer (David Janssen). Fans disagree on the model for the Kirk Douglas character, some even claiming he was based on this film's producer, Howard W. Koch.
The character of January Wayne (Deborah Raffin in this filmed Jacqueline Susann adaptation is recovering from a near fatal motorcycle accident. The actor Brian Kelly, who had originally been cast as "Robin Stone" in the earlier Susann 1971 adaptation The Love Machine (1971), was seriously injured in a motorcycle accident just prior to shooting and had to withdraw from that movie.
This picture, based on a trash pulp fiction novel, actually got Oscar nominated for Best Supporting Actress for Brenda Vaccaro. She did not win, losing to Lee Grant for Shampoo (1975), but Vacarro did win the Golden Globe Award in the same category.
Many movie posters for the film featured a preamble that read: "Jacqueline Susann's bold best seller that explored the avenues and darkest alleys of love among the international set. 'Once Is Not Enough'."
In the Autumn (Fall) of 1974, the year before this film first debuted, source author Jacqueline Susann had gone on an extensive book tour for this movie's source novel, even though she knew she was terminally ill with breast cancer.
"How old are you?" - David Janssen says this line to two different female co-stars in two different movies 14 years apart. In Once Is Not Enough (1975) his character Tom Colt is talking to January Wayne. The other movie is Ring of Fire (1961), and his character Sergeant Walsh is talking to Bobbie, a troubled teenager. Neither gives him a straight answer.