Comment by kovac

The failure rate doesn't need to be 0%. If the solution is good, at least it'll be close to 0% which means that it'd be possible for the vendor to provide better support for the small number of mistakes so that they can be clearly explained to the affected party and rectified more quickly. If the failure rate is too high to make better support infeasible, then the current solution is not really a good one and we need to consider a revision.