Yes, we all knew that.
Thrown spears or knives is not a process significantly affected by Bonus Rate of Fire, Bonus Hand to Hand Attacks, or Slayer. I'll yet test Sniper, though this isn't the optimal character build for such an effort.
I thought y'all might wanna know, though.

Oh yes, and one other thing. Some monsters fall such that you can't retrieve spears very easily, and throwing knives are sometimes lost forever for lack of being able to draw the cursor's attention to the damn things.