A third straight day of marathon negotiations between Hollywood studios and striking screenwriters ended on Friday night without a deal. But the sides made substantial progress, according to three people briefed on the talks.

The sides reconvened on Saturday.

The Friday session started at 11 a.m. Pacific time at the suburban Los Angeles headquarters of the Alliance of Motion Picture and Television Producers, which bargains on behalf of the major entertainment companies. For the third day in a row, several Hollywood moguls directly participated in the negotiations, which ended a little after 8 p.m.

Robert A. Iger, Disney’s chief executive; Donna Langley, NBCUniversal’s chief content officer of Universal Pictures; Ted Sarandos, co-chief executive of Netflix; and David Zaslav, the chief executive of Warner Bros. Discovery had previously delegated bargaining with the union to others. Their direct involvement — which many screenwriters and some analysts said was long overdue — contributed to meaningful progress over the past few days, according to the people familiar with the talks, who spoke on condition of anonymity because of the diplomatic nature of the efforts.

During the Thursday negotiations, the sides had narrowed their differences, for instance, on the topic of minimum staffing for television show writers’ rooms, a point that studios had been unwilling to engage on before the guild called a strike in early May.

The Thursday session took a turn, however, after the sides agreed to take a short break at roughly 5 p.m., according to the people familiar with the talks. The executives and studio labor lawyers had expected guild negotiators to return to discuss points they had been working on earlier. Instead, the guild made additional requests — one being that a return to work by screenwriters be tied to a resolution of the actors’ strike.

The actors’ union, known as SAG-AFTRA, joined writers on picket lines on July 14. Its demands exceed those of the Writers Guild. Among other things, the actors want 2 percent of the total revenue generated by streaming shows, something that studios have said is a nonstarter.

Several hours after talks ended on Thursday night, the guild emailed its membership to say that the sides would meet on Friday.

“Your negotiating committee appreciates all the messages of solidarity and support we have received the last few days, and ask as many of you as possible to come out to the picket lines tomorrow,” the email said.

The guild extended picketing hours on Friday to 2 p.m. Pickets have typically ended at noon.

In Los Angeles, several hundred writers turned up to picket outside the arching Paramount Pictures gate, far more than in recent weeks. The Writers Guild and SAG-AFTRA have been staging themed pickets to keep members engaged, and the theme on Friday happened to be “puppet day,” meaning that, in addition to picket signs, some marchers held felt hand puppets and marionettes. The mood was optimistic.

Outside Netflix’s Hollywood offices on Friday afternoon, picketing writers even began offering goodbye speeches, delivered via bullhorn. At the CBS lot in Studio City, the theme was “silent disco,” with several hundred writers dance-picketing while wearing headphones.

The talks were mostly back on track by the time picketing ended on Friday, according to two of the people familiar with the matter. On the sticky issue of minimum staffing for television shows, the sides were discussing a proposal in which at least four writers would be hired regardless of the number of episodes or whether a showrunner felt that the work could be done with fewer. (Earlier in the week, studios were pushing for a sliding number based on the number of episodes.)

They were also discussing a plan in which writers would for the first time receive payments from streaming services — in addition to other fees — based on a percentage of active subscribers. The guild had originally asked the entertainment companies to establish a viewership-based royalty payment (known in Hollywood as a residual) to “reward programs with greater viewership.”

The writers have been on strike for 144 days. The longest writers’ strike was 153 days in 1988.

“Thank you for the wonderful show of support on the picket lines today!” the guild’s negotiating committee said in an email to members late Friday. “It means so much to us as we continue to work toward a deal that writers deserve.”

Nicole Sperling contributed reporting.