Still, current and former employees said departures were common.

Ariadna Phillips-Santos, 34, taught kindergarten and first and second grades at Success Academy Harlem 5 from 2010 until 2012. Having worked in public schools, she was impressed by the academic rigor and the plentiful supplies. But she was raising a young son on her own, and juggling his care with her long work hours was almost impossible, she said. Ms. Phillips-Santos, who is now a dean at a public elementary and middle school in the Bronx, said she recalled asking her Success principal one day if she could leave at 4:55 p.m. — after the students had been dismissed — because her son’s day care had called saying that he had a fever and was vomiting, and being told, “It’s not 5 o’clock yet.”

Ms. Moskowitz said that Success was accommodating to working parents. She said that Success allowed some teachers and even some principals to work part time and that the network offers a month of paid maternity and paternity leave.

Most of the former teachers interviewed, however, said that they left not because of the workload, but because they disagreed with Success’s approach, which they found punitive.

One teacher complained that she was expected to announce all of her students’ scores on practice tests, by asking those who had scored a four to stand up, followed by those with a three and then those with a two. The teacher and her colleagues persuaded their supervisors not to make students with a score of one stand up, but those students were still left conspicuously sitting down, she said.

At one point, her leadership resident — what the network calls assistant principals — criticized her for not responding strongly enough when a student made a mistake. The leadership resident told her that she should have taken the student’s paper and ripped it up in front of her. Students were not supposed to go to the restroom during practice tests, she said, and she heard a leader from another school praise the dedication of a child who had wet his pants rather than take a break.

“I dreaded going into work,” the teacher, who now teaches in a public school, said.

Other former staff members also described students having wet themselves, in some cases during practice tests. Two former staff members who worked at Success Academy Harlem West, a middle school, in the 2013-14 school year, said that they recalled having to go to the supply closet to get extra underwear and sweatpants, which were always on hand, for students who had wet themselves.

Ms. Moskowitz said that, to mimic the environment of the actual test, when students are not supposed to go to the restroom except for an emergency, Success has all students go to the restroom immediately before practice tests. But students are still allowed to go during tests, she said. She acknowledged that there were sometimes accidents, but attributed them to the challenges of sharing space in public school buildings, which meant the restrooms were sometimes several floors away.