For Mr. Landers, the consultant, mastering the logistics of food delivery has become something of an obsession. Before the pandemic, he would order from the delivery apps about twice a week, not unusual for a New Yorker. More unusual was what he did once the deliveries arrived: stick a thermometer into his food.

“My wife would get to the point where she was like, ‘Can we eat now?’” Mr. Landers said.

Since the pandemic forced restaurants to close their dine-in areas, he has offered free consulting sessions to owners who are trying to improve their delivery operations. And he has warned clients to keep a close eye on the economics.

“Make sure that you’re not losing two or three dollars on every order,” he said. “Because you’ll just go out of business even faster.”

At Bolero, Mr. Le-Khac said he was not sure whether he would continue offering delivery and takeout. It might not work financially, he said. And with New York now the epicenter of the pandemic, he’s concerned about the safety of his employees.

Last week, he closed the restaurant to regroup and consider the implications of continuing to offer delivery. “The margin of error is so small right now,” Mr. Le-Khac said.

If he decides to reopen, he said, he’ll probably switch from plastic containers to paper ones.

Kitty Bennett contributed research.