Are they continuing to do NCV tests? If so I'd find that puzzling after an ALS diagnosis. As Vincent said, NCV studies are designed to determine if there's a pathology of the nerves, e.g., MS. ALS is a motor neuron disease, not a disease of the peripheral nerves. So if there is an abnormality in the nerve conduction velocities that would normally be taken as indicative that symptoms such as weakness were due to damage of the nerve which enervates the affected body part rather than the motor neuron. It is possible, though not likely, that a person could have both an MND as well as another nerve pathology. What's puzzling is that if the doc(s) are confident in an ALS diagnosis, I can't see any point in continuing to do tests, such as NCV, that are typically among the very first done when investigating the cause of neurological symptoms.
May I ask if the ALS diagnosis was done by a neurologist who specializes in motor neuron diseases?