My opinion, the nascar radios certainly work, but the frequencies, drivers are only as good as what is in it. Im saying that every year there is at least a dozen or so changes as drivers changes teams, new drivers come in or teams go away.
Short of course most of the top drivers stay put and most often stay on the same frequencies.
Back in the days gone by, I had excellent success using a subscription available at
Racing Frequency Service
Over a several year period, I was able to load the provided data directly from the computer (website) into various Uniden scanners. Using the proper cable/adapters, I was then able to transfer said data from my scanners directly into similar unloaded scanners at the track (relatives and friends). For last second changes, you could phone racescanners.com right up to race time and manualy make last second changes.