The starter relay IS the battery, and "if not" should be "made to be."
Running too much stuff to the starter stud...........which moves.......with the engine.......can cause flexing which will loosen the stud. Even with factory wiring, occasionally this was a problem, and is, in part, why the factory cables were molded together at the terminals
Running to the battery directly is OK if you can figure out a way to properly terminate it. I tend to keep "other connections" off the battery because of corrosion problems. Far easier to keep an simple battery clamp in shape
Ignore the screwdriver. Trying to illustrate the factory molded cables