In its sixth season, “Hawaii Five-0” continued to do yeoman work for CBS, winning its Friday time slot every week and averaging 8.71 million viewers an episode.

The average, based on Nielsen numbers provided by the network, is the lowest in the history of the rebooted version of “Five-0,” which finished its first season with an average of 11.24 million viewers when it aired on Monday nights.

“Five-0,” whose season finale aired Friday, peaked this season with Episode 13, drawing 10.07 million viewers Jan. 22. It hit matching lows twice: 8.01 million viewers March 11 and April 22.

All of those episodes benefited from viewers who recorded the show and watched it sometime during the following seven days. Through April 29, “Five-0” averaged 2.7 million additional viewers who watched an episode they recorded.

CBS renewed the Hawaii-based series for a seventh season.

“It doesn’t get especially huge ratings, nor does it get low ratings,” said professor Robert Thompson, founding director of the Center for Television and Popular Culture at Syracuse University in New York. “It’s one of those workhorses on the TV schedule that continues to plug away.”

This season’s viewer numbers ranked “Five-0” 27th among prime-time shows and 11th among CBS shows, but more important, it has won its time slot every Friday since CBS changed the schedule in the fall of 2013, Thompson said. That bodes well for the future of the show, he added.

“That could be one of the reasons it keeps going,” Thompson said. “If it is consistently beating what the other networks are putting out, you have to be in a really strong position and confident in your new shows to cancel a show that is winning its time slot.”

A seventh season wasn’t a surprise to Thompson, a regular viewer of “Five-0,” but it comes with good and bad news, he said.

“If you get through six seasons, the good news is that means you have an identity,” he said. “People know you exist. Six seasons is six years of promotion and gathering an audience.”

But characters start to grow stale, and that becomes apparent to fans when the cast is small, as in “Five-0,” Thompson said. Its main focus is the relationship between McGarrett (Alex O’Loughlin) and Danno (Scott Caan), he said.

“Essentially, it’s a buddy show,” Thompson said. “There is a sense that after six seasons of watching those two love each other and hate each other, at some point it gets hard to maintain.”

“Five-0” shot 25 episodes during Season 6, but actor Daniel Dae Kim, who plays Chin Ho Kelly, said the work schedule was better than in previous seasons.

“I wasn’t as exhausted at the end of the season as I have been in the past,” said Kim, who is spending the hiatus between seasons on Broadway, starring as the King of Siam in “The King and I.” “I felt this season was easier for Chin. There were new characters, so the workload for us was less. I appreciated having more of a life.”