It's important to have some sort of fail safe mechanism whether a fuse wire, fuse or circuit breaker inline between the battery and the voltage regulator.
Else you can unsuspectingly experience a experience a dead short, melted wiring or even watching your bike go up in flames (literally).

Horn brackets that are mounted along with the key switch between the cylinders has been known to cause meltdowns.
The fact of the bracket breaking (due to being loose, vibration, age etc,) isn't the problem.
The key switch terminals are bare ended (no insulation).
Should the horn bracket break, the horn will (most likely) swing down & rest on the back of the ignition switch for awhile, shorting the terminals.
The subsequent dead short heats up the wires, melting them and triggers the carnage shown below.
At this point, the motor is dead, no lights, no nothing. You're stranded on the side of the road, wondering just what happened.

This happened to a 74 XLH:
Here is the 'before' pic of the horn / switch brackets (taken ≈ 8 months prior to my catastrophic event).
The ends of the ignition switch wires were heat-shrink'd immediately after this pic was taken.
The screws on the back of the ignition switch remain exposed.
Note the relative pristine condition of the horn mounting bracket, p/n 69129-72.

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