We use the following system (a visual check - sorry, doesn't seem to be a way to automatically audit using ArchiCAD)
1. Set each Zone to have cover fill ON (50% foreground pen and zero background pen), and Zone contour line ON (we use a 0.25mm red pen)
2. Set a model view option (pre v20)/graphic override with no zone category fill
Overlapping % fills show up as darker colour. If the zone boundaries are not correctly aligned, the contour lines also make this obvious
ArchiCAD 24 (build 5004)
MacBook Pro (16-inch, 2021) Apple M1 Pro 32GB RAM | MacOS 12.0.1
Melbourne, Australia