My first headlight failure was approaching a cattle grate at night on fast dirt. About 100' from it, everything went black, i felt the grate and then got on the brakes and tried to remember where straight was. After a while my eyes adjusted enough to ride the rest of the way out.
Now i have 2 H3's one wired through the stock harness, and another with a separate power source and relay. The only common point they share is the hi/lo switch. I can run one at a time, or both if i select the "middle" I had a bulb go gout on me once, and anuter time i had a short up front when a connector wored loose that took out the fuse to the direct wired light. Both times i still had at least one light working.
I carry 2 extra bulbs. Having some sort of backup lighting is definitely a good idea, adding a small set of running lights to the stocker for extra offroad illumination or going with a twin headlight setup. Twin headlights rock!