that's exactly what I Was saying... speed due to thin necks IS important with guitarists... much moreso than most bassists. We don't utilize those extreme techniques like guitarists do, and a thin neck is the difference between doable and maintainable without strain versus being able to do it but not keep it up without strain.i mean, i think if someone is "faster" than billy the difference would be negligible. not that "fast" in and of itself is meaningful in a musical sense, but it's part of this discussion.
i can't recall who i first learned this from, but if you place your hand in front of you (air-bass) as if you were playing, moving fingers 1 and 4 up and down as if you were fretting, move your thumb closer and further from your hand. notice the thumb distance to the hand has zero impact on the movement of the other fingers?
thicker neck would certainly have physical repercussions, just like anything else. the thumb being slightly further away from your hand, to my understanding, has no direct influence on your ability to move your fingers quickly.
i'm sure there could be something i'm missing. but i just struggle to find a logical reason why a thinner neck would facilitate faster movement?
So regardless of how fast Billy is, he is definitely a common name with fast playing on bass. But he's not fast compared to really fast guitarists... he can keep up in some techniques, tapping and finger picking etc along with standard fast left hand fingering techniques for speed that we all can do with practice. But it'll be different for some other complex techniques.
Again, I mean that for extreme shredding techniques on guitar. Truly fast guitarists (not the fast players we hear in rock, but the true speed players) play MUCH faster than bassists, even faster than Billy. So that is where neck thickness can make a critical difference, although again it is STILL just up to personal preference. Everybody is different. But thin does assist with specialist guitar techniques.