The author, Alan Naar, has prepared an excellent summary of Rule 36, which controls requests to admit.
He has also summarized the relevant New Jersey Rule.
He is correct that requests to admit are a useful litigation tool. They can be used to obtain admissions that a document is genuine or that a document is a business record. They become problematic when used too aggressively to obtain admissions about facts that are in dispute. The other party will deny them and the party seeking the admissions will have obtained nothing.
Also, remember that in Illinois the number of requests to admit is limited to 28.
Edward X. Clinton, Jr.