An example of how important neck training is, is my own experience. I've done Judo and Jujutsu for over 40 years along with the neck bridges and strengthening exercises that accompany it. Several years ago, I was helping someone teach a class on kesa gatame and showing how you could be rolled backwards if you didn't position your legs properly when the guy whose class it was rolled almost 90 degrees from the position he should have taken and put his entire body weight on my neck in a bent position.
$2000 worth of chiropractic work later, I was able to get back onto the mats for groundwork, but I still have neck trouble from the injury.
If you're going to do BJJ, Judo, or Jujutsu groundwork, there is nothing more important than neck conditioning. Even with it, there is a very good possibility you will come up with a neck injury at some point. The better shape your neck is in, the better the results of protecting yourself from those injuries.
