it would only matter if you have different gauge wire sizes and ones in which are not large enough for the draw example 2 8 gauge and a six gauge. 8 gauge is good for about 40 amps and a six is good up to about 80 amps theres about 160 amps passible - heat and resistance however if a crappy fuse blows and you loose a feed extra power might be forced through a feed then you blow multiple fuses. besides you shouldnt need anything larger than 1 gauge per alternator running to extra battery because you would need excess of 250 amps per alt and most competition alts push around 175 -225 amps max unless your nuts like me trying to built those 350's