IMHO, the ground system is very important and the factory wiring is marginal at best.
I would look at the EVTM and ascertain which drivetrain components would benefit from a better ground path. Many critical components do not have a frame or 'component' ground and have an actual ground wire which is spliced into the wiring in one or more places.
Keeping the factory grounds clean and tight is critical as well as inspecting battery cables for any internal corrosion.