Last year, Starbucks vowed to provide store employees with more consistent schedules from week to week, and to post their schedules at least 10 days in advance. The company said it would stop asking workers to endure the sleep-depriving ritual known as a “clopening,” which requires them to shut down a store at night only to return early the next morning to help open it.

But Starbucks has fallen short on these promises, according to interviews with five current or recent workers at several locations across the country. Most complained that they often receive their schedules one week or less in advance, and that the schedules vary substantially every few weeks. Two said their stores still practiced clopenings.

The complaints were documented more widely in a report released on Wednesday by the Center for Popular Democracy, a nonprofit that works with community groups, which gathered responses from some 200 self-identified baristas in the United States through the website Coworker.org.

“We’re the first to admit we have work to do,” said Jaime Riley, a company spokeswoman. “But we feel like we’ve made good progress, and that doesn’t align with what we’re seeing.” Ms. Riley maintained that all baristas now receive their schedules at least 10 days in advance.