Part mindmaps and surah mindmaps do not compete. They operate at different scales.
A surah map gives local structure. A part map gives large-scale orientation across a wider territory. And above those, Quran Life also uses the meta mindmap layer, which helps you keep track of the broadest structural picture beyond one ordinary part map.
So the relationship is not either-or. It is zoom level. Surah mindmaps help you navigate inside the surah. Part mindmaps help you see how several surahs or sections belong together. The meta mindmap helps you think about the larger frame in which the parts themselves sit.
This matters because students often lose stability not only inside one surah, but also at the boundaries between surahs, parts, and broader structures. Each layer supports the one below it.