I have never heard of people using method patents to sue over methods other than things similar to methods in the claims. Usually, the claims are as general as you can get away with, and cover a lot more than just the actual "X" that they are introducing to the market. When someone does something similar to "X" without reading the patent, they can easily be walking in one of the claim sets that has been patented in the "method to do Y" patent. Most people who want to copy something do it in a fairly unoriginal way.

Still, patent claims are never as broad as "drug to alleviate headaches" or anything similar.