Industrial Ziegler–Natta catalysts for polypropylene production are complex formulations with a reputation for being “black boxes”. In this paper, we report the results of an extensive investigation of the three latest commercial generations, performed with advanced high-throughput experimentation tools and methods. The thus obtained database of structure–property relationships, of extraordinary width and depth, provided a high-definition picture of the screened systems, allowing us to highlight important details of their inner workings. In particular, the delicate relationship between surface coverage and lateral steric pressure on the stereoselectivity of the catalytic species, as well as the role of chemisorbed donor and Al-alkyl species on said parameters for different formulations, was revealed.