You might not be able to tell from the picture but it's tight area between two/three foundations and a retaining wall. Kind of boxed in a small area. 45 would be hard to keep the distance between them. But the rock is no more or less conductive than the soil, probhably more so. This stuff being serpentine, most of it is ancient compacted soil anyway.
Either way going at 45 degrees can also lead to the same problem very often. Once drove ten rods to get two of them down once. Ended up with 8 steel stubs to cut off.
