A century ago, the misery of New York’s urban poor was embodied by the iconic scene of the morning “shape-up” at the docks, where rough-hewn longshoremen lined up anxiously to see if the boss would pick them for that day’s crew or turn them back empty-handed. These days, the city has a different kind of shape-up—a less visible mill of workers staffing its bustling boutiques and vendors. Instead of assembling at the waterfront, they call the manager to find out how many hours they can get on a given day—stressing about whether they’ll clock enough hours this month to make rent, or hoping their next workday doesn’t interfere with their school schedule or doctor’s appointment.

This anxiety of living not just paycheck to paycheck but hour to hour is the focus of a new policy brief on the impact of unfair schedules on wage workers. The report, published by the progressive think tank Center for Law and Social Policy (CLASP) and the worker-advocacy groups Retail Action Project (RAP) and Women Employed, reveals the flip side of the “flexibility” and “dynamism” of twenty-first-century retail: the tyranny of a work schedule that changes day by day, hour by hour.

On top of the economic hardships of working a part-time job that does not pay a living wage, retail workers are often further burdened by the stress of the on-call schedule: they must call in first to see if hours are available, wait for word from the boss and, sometimes, end up with just a four-hour shift. The labor of the whole ordeal might then be offset by the financial costs of commuting and the disruption of their entire day. Ironically, while this scheduling structure brings chaos to workers’ lives, it stems from a hyper-mechanized system of computerized staffing. With huge employers like Walmart and Jamba Juice, this Taylor-style “efficiency” programming often leaves workers at the mercy of variables like the weather (a hot day demands reinforcements for a lunchtime juice rush) or consumer whims (a slump in sales means temporarily downsizing the sales-floor staff). Even full-time workers might get saddled with erratic shifts, or are pressured to work extra hours on short notice.

These strenuous schedules reflect the “just-in-time” business model and the parallel “need it now” consumer culture. Ever-fluctuating schedules are designed to react instantly to every fad and seasonal spasm of the market, which ties into a frenetic global manufacturing system, stretching from sweatshops in Bangladesh to Fifth Avenue show floors.

The erratic labor structure robs workers of control over their lives. Being constantly on call, without set hours, makes it extremely hard to budget for basic living expenses like housing and childcare, and sometimes nearly impossible to plan for, say, saving for college. And for the working poor, irregular schedules can undermine access to safety-net programs and benefits, which are, sadly, a key resource for many low-wage retail workers, who earn so little that they must rely on public programs. Working too few hours, according to the report, “may limit their eligibility to claim firm-provided benefits like health insurance and sick days.” And paradoxically, if they do cobble together enough hours to pay the bills, they may then wind up earning too much to qualify for Medicaid benefits.

To upend the cycle of high stress and sinking morale, a coalition of community and labor groups has launched the Just Hours New York campaign to push for fairer work schedules through state and local legislation as well as worker organizing—particularly at low-wage, nonunion workplaces. Potential policy solutions include minimum-hours requirements, a more stable schedule and “reporting pay” policies, which ensure that on-call employees get some amount of pay even if their schedule has been disrupted. Firms could also be required to provide more advance notice of changes to schedules.

Some unionized outlets already have these practices in place. At Bloomingdale’s flagship New York store, for example, part-timers, who are covered by a Retail, Wholesale and Department Store Union contract, are guaranteed at least twenty hours weekly and twenty-one days’ advance scheduling notice. The CLASP/RAP/Women Employed report points out that more-stable work schedules are good for business as well, by helping to relieve employee stress and high turnover rates, thus stabilizing the whole supply chain.

Although it claims to maximize workplace efficiency, the “just in time” system exploits work time as a commodity. A just schedule takes into account the true value of a worker’s time, on and off the clock. It’s the only way to ensure a fair day’s pay.