University of Southern California, agreed with her seven roommates that significant others had to test negative for the coronavirus within “a couple of days” of entering the premises. Friends could visit, but only if they sat around the fire pit in the back of the house. The housemates were not allowed to ride in cars with people outside of their bubble.

Because of those rules, Ms. Andrews’s campus social circle has shrunk dramatically. As an art major, she used to know everyone in her major, because they would meet during studio time. But she is delighted to have made non-college friends while roller skating in her neighborhood, known locally as the El Salvador Corridor, meeting people she might not have been as open to if not for the pandemic. She makes roller skating dates via Instagram with a couple of teenage girls who live nearby.

Xanthe Soter, a junior at Temple University, said she “thrived” academically this year, because there were so few distractions, and because she was able to manage her time more efficiently. “I had my best semester,” she said. “I didn’t have to worry about the little tidbits of getting up, getting dressed, going in person — it was very draining.”

Hunter College in New York City, chafed at not being able to meet her professors, and said many of them gave online lectures in which they were “talking to themselves, nonstop.”

As an international student living alone, she has felt painfully isolated. “It’s like I live on an island,” she said.

Many colleges restricted on-campus socializing to small groups of students housed together, which made for a kind of exclusivity, said Maria Gkoutzini, a freshman at Williams College. “Friendships were a lot more cliquey,” she said.

“The most difficult thing for me was just knowing that that’s not how it usually was, but not being able to picture anything other than that, because that’s all that any of the first-years knew,” she said.

Almost everyone said they had changed their outlook on careers and the future. Getting ahead no longer seemed as urgent, the path less clear. Julia Petiteau, Ms. Soter’s roommate and a marketing major at Temple, said she knew students who had lost internships during the pandemic summer and taken jobs at supermarkets or Home Depot just to fill the gap. Now jobs are opening up, she said, “but it’s tough to put an internship that got canceled on your résumé.”

Many students, especially at elite schools, took a gap year rather than face the uncertainty of college in a pandemic. And for some of them, the timing was just right: For all the celebration of campus life, the college experience even before the pandemic had included a certain amount of insecurity and anxiety.

Yale, said the pandemic saved his mental health by allowing him to take a year off without formally asking for a mental health leave. His freshman year, he had been paralyzed by perfectionism and anxiety, he said. The break had allowed him to recover enough to feel comfortable returning in the fall. “Covid, horrible as it is, honestly saved my life,” he said.

Speaking from 400 miles into the Pacific Crest Trail, as she hiked from Mexico to Canada, Mimi Goldstein, who would have been a sophomore at Duke, said her gap year had made her let go of her many security blankets. “I think a little time and distance made me realize how much energy I spend jumping through other people’s hoops.”

The pandemic had a paradoxical side, she said. “This is definitely a dark spot in American history, but personally, it’s been a good shake-up,” she said. She had dropped out of her sorority. She was thinking of changing her pre-med major to global cultural studies.

“I was very much in this sort of Greek life, pre-professional, glitz and glam. I knew it wasn’t a perfect fit for me, but it gave me some social security, which you know doesn’t exist, and financial security, which you know doesn’t exist.”

She said she was still figuring things out. “There is a very, very real chance my parents will kill me,” she said.

Sheelagh McNeill contributed research.