Those circuit breakers will cycle only a limited number of times before failing completely. Circuit protection is meant to prevent fires. Resetting circuit breakers equal striking match after match in my opinion.
The ones i was looking at are a manual reset. If you ran your lights with relays and a fuse, when the fuse pops its like a manual reset breaker popping anyway, except you need to carry spare fuses. Either way your headlamps are gonna go out if theres a problem.
Yes, you want to wire the circuits with seperate circuit breakers for high and low beam. Thats the smart thing to do. I am just thinking about the issue of being out in the middle of nowhere, and not having spare fuses. Or burning em all up trying to figure out the problem while on the side of the road.
But you bring up a good point, is there a cycle life on them, and what is it? Does that depend on the brand? Obviously chinese ***** gonna prob fail faster, but at what rate? If your wiring is routed properly, and wrapped, how often is this issue really going to come up. I have seen some awful wiring jobs myself tho, so i guess it does.