Claim chart are used to depict the real world product or service that is infringing your patent claim. The depth of claim-chart can be dependent on how it will be used. For instance, generalized claim chart or “Evidence of Use”, may provide an overview of a patent claim and how a family of product or material may be covered by those claims.
What the claim-chart seem to accomplish is avoiding the hasty conclusion by a patent owner that “it’s obvious the product infringes” or by the alleged infringe that “it’s obvious our product is different from patent owner’s product.”
They are helpful to evaluate strength and weakness of one’s position, thus they are helpful in avoiding expenses when one’s position is weak.