I encourage everybody to hit their forearms directly.

I have been training mine directly for 6 months and they have grown a lot. I include 4 sets of reverse curls and 4 sets of forearm rope rollers (pictured below) at the end of my Back/Bi workout, twice a week. I used to assume they would just grow from training back/bi as an accessory muscle but since I have focused on them individually they have blown up. Pics to follow.