In a larger helo, this becomes progressively more difficult and a run on (at some speed) is inevitable - usually because the amount of nose up required to wash off all the speed will, in all probability, smack the tail into the ground and rather aggravate the situation, or leave you quite high with decaying Nr.
Do you consider a Chinook to be a "larger" Helo?
Why is a Run On landing inevitable?
By "inevitable"...you mean to say every single time no matter the conditions?