LOS ANGELES — The lead producer of the 91st Academy Awards, Donna Gigliotti, was in high spirits on Friday morning. Serena Williams had been confirmed to appear on the telecast in a moment involving “A Star Is Born.” Thousands of red roses for the set were en route. With nine days until showtime, everything seemed to be coming together.

Then her phone rang.

Officials from the Academy of Motion Picture Arts and Sciences were on the line. They told her that they were bowing to pressure and abandoning their plan to shorten the ceremony by awarding four trophies during commercial breaks, with the winning moments being edited and aired later in the show. Gigliotti would have to quickly retool the broadcast so that every Oscar was presented without edits, in the traditional manner.

And the officials had a question: Could she still deliver a three-hour telecast — max? Pretty please?

“The answer was no,” Gigliotti said over the weekend.

The film academy has been fighting over how to keep the Oscars to a reasonable running time since at least 1987. The reason is simple: protecting television ratings. After three hours, academy research has shown, people on the East Coast go to bed, dragging down overall viewership numbers. People on the West Coast also move on. Three hours of watching Hollywood celebrate itself — last year’s show was nearly four, not counting red-carpet coverage — seems to be most people’s limit.