The production of illuminated manuscripts in the royal library of Iran’s workshops began with comprehensive planning of the entire structure by the workshop head. This planning aimed to coordinate among calligraphers, painters, and illuminators to organize the manuscript and determine the illustrations’ placement and their integration with the main text. Beyond surviving works and general knowledge about art workshop organization in various dynasties’ Royal Libraries, limited information exists about this process and its implementation. This study employs Quantitative Codicology to analyze relationships between chapters, sections, couplets, and miniature positions to reveal the internal structure of The Shahnameh of Shah Tahmasp (Shahnameh Shahi), Iran’s national epic and a masterpiece of the royal Library of Safavid dynasty (Safavid Ketabkhaneh), during 16th century. The findings reveal the manuscript’s initial structural concept, designed by chief supervisor Sultan Muhammad, and the transformations that occurred when two subsequent supervisors took charge during its extended production period. His original rhythmic arrangement, which aimed to maintain miniature folios within specific couplet intervals, evolved into event-oriented and uniform distribution patterns under Mir Musavvir and Aqa Mirak’s respective supervision. These changes are examined through hypotheses considering both internal and external variables that can reveal the reasons behind the manuscript’s organization and its changes