Fuse the Wire or Fuse the Device?

I am about to open a debate on fusing in Gliders. Which of the
following fusing methods do you believe should be used and why?

1) Place one fuse at the main battery sized to protect the wire. That
is if the wire "fuses" (vaporizes) at 20A then the fuse should be 20A.
Therefore it takes a 20A device fault to blow the fuse.

2) Place one fuse at the main battery sized to the devices being
sourced. That is if all the devices being powered have a maximum draw
of 5A, then the fuse should be 5A or slightly larger. Therefore it
takes a 5A fault to blow the fuse.

3) Place one fuse at the main battery sized to protect the wire (see
#1). Place one fuse at each device sized to the devices being sourced.


4) Place one fuse at the main battery sized to the devices being
sourced (see #2). Place one fuse at each device sized to the devices
being sourced.

5) fill in the blank

Thanks, John