Testing code is important because we know, from previous experience, that code written by humans tends to have bugs. In this case, we also know from experience

Testing code is important because we know, from previous experience, that code written by humans tends to have bugs. In this case, we also know from experience that small devices like iPads do not cause high levels of EMI. Once we have tested a dozen models on a dozen planes and had successful results on all 144 tests, there is no need to test further models. This is unlike software, where of 144 unit tests, a good percentage are almost guaranteed to fail at some point in time.