Same here. I would look into a better fuse holder and next time once a month or so just go over your connections to ensure they are still good.
As for multiple wires, there is minimal use if he does not need that much current. 90% of the members on this board do not need to run more then one single run of 1/0. I also would not condone ditching all fusing when running wires the length of the car. That is simply asking for an issue to arise(I hope it never does to anyone).