The redundant theory like airplanes have. Having two, in case one fails you have a backup.
I understand and appreciate your point of view and fully understand your above statement about redundancy since I spent over 13 years flying on B-52's. With 8 engines, at least a dozen hydraulic pumps, 4 generators and god knows how many fuel pumps, the "BUFF" is a case study in the concept of redundancy.
The units where I was assigned always had both B-52 bombers with 8 engines, and KC-135 air refueling tankers with 4 engines. Having 4 or 8 engines gives one a large comfort factor knowing if you loose one or 2 engines, there are still enough left to keep you in the air and get you home. But because B-52's had twice as many engines as KC-135's, the guys from the engine shop always spent twice as much time changing engines on B-52's vs KC-135's.
The point is that you could have a hundred alternators and never have to worry about being dead on the side of the road for lack of electrical power. But you'd spend all your time changing alternators, one here, two there.
Redundancy is great, but if you double the equipment, you double the maintenance. One just needs to make sure the equipment, or in this case, a single alternator is up to the task at hand and has the capacity to do the job.
