The planning paradox: Why engineer-to-order companies must embrace contradictions in tactical planning

Tactical planning practices, like request for quotation (RFQ) planning and sales and operations planning (S&OP) are critical for competitiveness in engineer-to-order (ETO) settings yet remain understudied compared to repetitive manufacturing. This study explores RFQ planning and S&OP practices in ETO settings through integrated paradox and contingency theory lenses, addressing how experienced contradictions affect these practices and how contingency factors influence contradictions and practice design. A multiple case study of five Swedish companies reveals that ETO organizations face nine general and seven context-specific contradictions shaping their tactical planning practices influenced by seven contingency factors grouped into fundamental, mediating and operational levels. The findings challenge static views of organizational fit, revealing a four-stage iterative cycle where contingency factors manifest contradictions that shape RFQ planning and S&OP practices, which subsequently become new contingency factors. This dynamic relationship suggests that effective RFQ planning and S&OP practices in ETO settings requires embracing rather than resolving inherent contradictions through continuous adaptation and sophisticated management. S&OP emerges as a powerful contradiction synthesis mechanism when properly designed for ETO settings. The study extends paradox theory to tactical planning domains, advances contingency theory by revealing practice-contingency co-evaluation.