Observations on munitions workers are organized to examine the relationship between their output each week, their working hours and days each week, and their working hours and days in adjacent weeks. The hypothesis is that workers need to recover from work, and a long working week results in greater fatigue and stress, and yet provides insufficient time for recuperation before the next week's work opens. Workers require time off the job to restore their physical, mental and emotional capacities, and if a long working week provides inadequate time to repair, then their subsequent work performance suffers.