Burnout as an Early Signal of Unsustainable Work Design: Integrating Job Demands, Effort–Reward Imbalance, and Illegitimate Tasks in Thai Manufacturing

Although organizational behavior (OB) research on burnout has traditionally emphasized workload and resource imbalance, such explanations remain insufficient for understanding burnout in highly routinized industrial hierarchies, where work is standardized, autonomy is limited, and stress often arises from how tasks are assigned and justified rather than from workload intensity alone. Drawing on the concept of illegitimate tasks—tasks perceived as unreasonable or unnecessary given one’s formal role—we argue that burnout in industrial hierarchies is more fundamentally rooted in violations of role legitimacy embedded in work design. We employed an explanatory sequential mixed-methods design to understand how job demands, effort–reward imbalance, and illegitimate tasks collectively affect job satisfaction and burnout in large manufacturing organizations. We analyzed quantitative survey data collected from 504 employees and found that illegitimate tasks exert a stronger, more consistent effect on burnout than effort–reward imbalance. In addition to these findings, qualitative interviews with senior executives revealed how ambiguous role boundaries, intensive overtime practices, and limited advancement structures normalize illegitimate task assignments in industrial settings. The findings suggest that burnout in industrial settings reflects not only accumulated job demands but also employees’ evaluations of how their work roles are structured and valued. This study thus brings the stress-as-offense-to-self perspective into OB scholarship and demonstrates its relevance for theorizing burnout in routine industrial work. The findings indicate that burnout reflects deeper deficiencies in work design that may undermine the sustainability of industrial work systems. From an industrial workforce sustainability perspective, workplace burnout extends beyond an individual health concern and signals structural issues in job design and human resource utilization relevant to social sustainability and decent work. Burnout can serve as an early warning indicator of declining human capital sustainability.