Ever since Orchard Collegiate Academy was assigned to the city’s Renewal program for low-performing schools, leaders of the Manhattan high school have worked to boost attendance: meeting weekly to hone their strategy, and teaming up with a community organization to contact families to find out why certain students aren’t showing up.

The effort seems to be paying off. The school’s attendance rate increased from 76.6 percent two years ago to 81.5 percent last year, just barely meeting its assigned attendance goal (though still well below the city high school average of nearly 88 percent).

But while Orchard Collegiate — and the 85 other schools in Mayor Bill de Blasio’s signature turnaround effort — are expected to maintain progress, they were not issued new attendance goals through the Renewal program. Nor did they receive official goals on the quality of the school’s leadership, classroom instruction or school climate, benchmarks that have been issued for the past two years.

Education officials say this is intentional: As the program nears the end of its third year, they argue, it’s time to shift focus toward academic outcomes like state test scores and graduation rates.

Yet even staunch supporters of the city’s approach to school turnaround expressed concerns with that model. They worry that expecting academic gains too soon will set the program up for disappointing results on a national stage, that it sends mixed signals to long-struggling schools over what the city wants them to focus on, and that the program’s success will be tied too closely to student test scores, which may not accurately reflect student learning.

“What they’re really saying is that schools should be showing outcomes in the second year of implementation, which is not realistic,” said Megan Hester, a senior associate at the Annenberg Institute for School Reform, who works closely with community organizations that partner with Renewal schools. “It’s a political timeline and not a school research-based timeline.”

The city’s shift toward evaluating Renewal on academic outcomes is part of a key de Blasio promise: that the program would yield “fast and intense improvement” within three years, spurred by social services like mental health clinics, social workers and vision screenings combined with extra academic support.

That overarching strategy — slated to cost $850 million through 2019 — won over many advocates who criticized his predecessor’s approach, which involved dozens of contentious school closures.

But those same supporters have long worried that expecting speedy transformation is unrealistic, given that schools in the program started out among the city’s lowest performers. Research has shown school turnarounds can take five to ten years, well beyond the city’s initial three-year timeframe, if they happen at all.

Figuring out how much progress is realistic to expect — and when — is a difficult task, experts say, complicating the city’s desire to establish incremental goals struggling schools can realistically achieve.

To thread that needle, the city assigned schools two different types of benchmarks. The first — called “leading indicators” in education jargon — looked at data like attendance and whether the school has strong leadership or rigorous instruction, as measured by surveys and observations.

Those goals were meant to offer initial signs about whether the turnaround efforts were taking hold. Progress on those standards has been uneven: 20 percent of the city’s 86 Renewal schools met none of their leading indicators last year, while 15 percent met all of them.

The second kind of indicators are called “student achievement benchmarks,” and focus on proficiency in reading and math as measured by state test scores for elementary and middle school students, and metrics like graduation rates and state exit-exam completion for high schools students. Some of those benchmarks require only tiny improvements, but many schools have still struggled to meet them.

“Certainly by the end of year three we expect to see noticeable improvements in student achievement,” Eric Ashton, the education department’s executive director for school performance, said in an interview. He and other officials stressed that the city would still pay close attention to attendance and school climate, and Renewal schools that did not meet last year’s goals are still expected to meet them.

Michelle Renée Valladares, associate director of the National Education Policy Center at the University of Colorado at Boulder, said she applauded the city’s initial focus on both school climate and academic goals, but worries about the shift toward academic outcomes measured by test scores.

She noted that boosts in attendance might actually have a negative effect on scores, and standardized tests are not ideal short-term measures of student learning.

“Now all these kids are showing up, who weren’t showing up and are probably behind, and now we want you to get their test scores up instantly,” said Valladares, who has advised the city’s education department on how to measure the program. “It doesn’t happen instantly.”

For now, multiple Renewal school leaders said the lack of new leading indicators was unlikely to change their work — at least in the short term.

“Right now, I feel like we’re doing all we can to raise attendance,” said one Renewal school administrator, who said his school was unaware that the city did not plan to issue new leading indicators this year, and spoke on condition of anonymity.

But, he added, the city’s shift might inspire a change of his own. “If they’re telling us we’re no longer measuring it,” he said, “does that mean we might move resources? Maybe.”

The benchmarks aren’t just a way of incentivizing schools to make certain changes, experts said. They have implications for the approach itself.

“Other people are looking to [New York City] about how do sustainable community schools work … and know they’re working,” said Valladares. “It’s really important for them to get it right.”