Actually this very much has been a permanent issue with decals, and various specific techniques had to be built to fight it, ranging from depth bias to using the exact same polygons as the object the decal's gonna be on (because that way the exact same z values will be output, avoiding z-fighting entirely) to deferred…
This could be left as split I think. Jordan - "more individual meshes = more draw calls." this is true, but it isn't true when we are talking about sub meshes or lets call them elements. "Preferably, you don't want to have floating/intersecting geometry as it leads to z-fighting." This also isn't completely true, then how…