Acording to the wiki
-All Special Abilities have 3 uses/day. This is due to bioware limitations make Special Abilities to be infinite uses/day, so any uses after the 3rd will have no effect.
The ogre can throw boulders an infinite times a day it seem.
And yes.. The ones after the third still do damages.
Please let this be working as intended. I didnt even know this form had boulders and now I want to throw boulders forever.
The wiki is not accurate. More powerful abilities tend to be limited. Minor damage effects are infinite. Boulder toss should do 1d6+strength damage with low DC reflex for half.