That answer and its brethren are very good answers. However, they become progressively less useful each time you use them in the same presentation. They are use

That answer and its brethren are very good answers. However, they become progressively less useful each time you use them in the same presentation. They are useful when you essentially do have mastery over your material, and you will therefore not need to dodge most questions with them. In fact, they are useful because, if used in the most sincere and literal way, they are a compliment to the person who asked the insightful question. (Of course, they are bad answers to the basic question about provenance asked by the GP - if someone was asking you where you got Graph X and you don't know, telling them that you'll talk with them later will be treated as the dodge that it is, not as a compliment.)