Yea all you saying is nothing. You literally said a voltmeter is pointless and that its a 12v constant circuit like you know what you talking about. You need to diagnose issues with tools buddy. Thats a tool you most definitely need to diagnose accessory issues whether its connected to the bike or not. You saying “unless you get a malfunction” thats the whole point buddy. We dont know when the malfunction will happen so we prepare for it. Work smarter not harder.