Other than requests for admissions on the authenticity of documents–which can be issued in unlimited numbers–South Carolina Rule of Civil Procedure 36(c) limits a party to twenty requests for admissions absent “good cause shown.” How to employ those twenty requests is an important strategic concern.
There’s really only two ways one can utilize a request for admission that does not involve authenticating documents: 1) get a useful admission from the opposing party; 2) get a denial that potentially challenges the opposing party’s credibility. Requests to admit that cannot conceivably do either are a waste of one of one’s twenty allowed requests.
Thus a request to admit something that is trivial is (probably) a wasted request. A request to admit something that is already acknowledged by the opposing party (typically in a pleading or affidavit) is generally redundant as one can “prove” that fact at trial through the opposing party’s acknowledgment. See SCRE 801(d)(2), which makes the use of a party opponent’s statements an exception to the hearsay rule.
A request to admit something broad or vague is also a wasteful request. Asking an opposing party to “admit or deny that you are an unfit parent,” “admit or deny that you are a horrible spouse” or “admit or deny that you regularly consume alcohol to excess” is almost certainly going to be met with a denial. When it is, there is little ability to impeach the opposing party on his or her denial. Anyone can give a reasonably explanation as to why they are not an unfit parent, a horrible spouse, or a habitual drunk. And, when faced with the denial and explanation, how can one prove the opposing party is a liar?
Thus, the ideal request to admit is: 1) not trivial; 2) not already acknowledged; and 3) narrow enough that an admission is useful but a denial is subject to impeachment. A request to admit that one in an unfit parent might better be reframed as “admit or deny that your untreated mental health disorder placed the minor child in danger on [date].” A request to admit that one is a horrible spouse is better reframed as a request to admit some horrible behavior or action. A request to admit that one consumes alcohol to excess might be better narrowed as “admit or deny that you were too intoxicated on [date] to safely drive a motor vehicle [or to safely care for the parties’ minor child].” Such requests are helpful if admitted and subject to impeaching evidence if denied.
The craft–and it is clearly a craft–of developing good requests to admit is so case specific that it’s impossible to create useful go-bys for such requests. However trivial, redundant or unimpeachable requests are rarely useful and should be avoided.