No shit, I'm a f@$king auto electrician for f@$k sake, Do you think I would honestly be that f@$king stupid to not select the right wire before wiring something up.. The reason why I said its dependant on the load, You are not going to put a 5A fuse in there and pop it the first time you plug something in.. Cable has to be selected to minimise voltage drop and carry the correct current load. You are not going use 4mm cable to wire your starter motor up now are you?
It is very important to have the fuse right at the battery, I made this a point because of reading the following
"I've run the one that come directly out of the back to the fuse, then battery. I one off to the side has been connected to a bolt that secures the tail light. "
Fuses are designed to blow in the event of a dead short, Say the wiring rubs through somewhere and touches the frame of the vehicle. No point in having the fuse right at the socket when you still have all this wire running along the vehicle back to the battery.