[A sample of] new breakers are tested at the factory for 10,000 tries.
You could test your breakers 100 times and still not be sure they will work on the 101st try.
BTW, consecutive successes with no failure is "right censored data", so to do the reliability calcs I guess they assume it would have failed on the 10,000 plus 1 try.
But, how often will a house breaker be called upon to trip?
This is the "mission length"; how reliable is a breaker that fails in less than 10,000 attempts when it only needs to work on 1 or 10 or 30 overloads?