Resistance. If you have a 3' line and 4' line. The 3' will carry more of the load. In higher voltages it's not as much of of a problem, but at 12v levels it can be an issue. It's general good electrical practice to keep all the lines as close to the same length asnll possible. Esp. If your fusing each line. Each of my pos 1/0 wires have have a 150a fuse to the inverter which is roughly 300a protection. If one cord was shorter it would carry more amps and blow the fuse when a balanced load would not. Thus blowing the second fuse too.