Good question. The discovery methods have no necessary connection, although you might notice that most requests for documents ask the other side to produce all documents “identified in your responses to interrogatories,” and many interrogatories from debt collectors ask you to explain why you denied any request for admission. I don’t usually suggest the question about requests for admissions because the only reason for denying a request for admission is that you don’t know it to be true. Period. But maybe a more sculpted question: “for every request for admission you denied, if you believe it to be untrue, state every reason…” Worth a shot, maybe.