I think the general rule of thumb is to limit connections to battery posts to the main cables themselves and a smaller gauge feed to your negative buss in the helm. Maybe it's best practice to terminate all grounds through the buss and limit excess connections at the battery post. The CG says:
"Grounding or bonding may be accomplished by connecting the metallic components electrically by running a wire from one component to the next, and so forth to the boat’s ground. Grounding can usually be accomplished by a connection to the common bonding conductor or the engine negative terminal".
That to me would indicate (on an outboard) that the negative buss should be established from the engine ground to the helm. I'm probably mistaken but it sounds that way. I know I don't have it wired like that.
I have two on my battery, one for the buss and one for the tank.
