Was the shiela practicing for a trip to 'Murica?
I can only think of a couple of things that could shorten the life of the starter.
If there is something odd about the mounting causing it to not engage the drive gear properly, it would wear out the bearings quickly.
If the relay is sticking, the starter would continue to run after the engine starts and wear out.
If the over-running clutch were to stick, the starter would be turned by the engine, which would destroy it in short order.
Or, it could be that someone buggered up his job building the motor in the first place so that things don't quit fit. It's rare, but it can happen.
