The last time I was regularly flying there was the early 80s and there was a surprising number of single NDB approaches. Having cut my teeth on them in Oz, I had no trouble with them but I found that Americans generally didn't like them and, for the most part, didn't have a clue on how to fly them.
I'd have thought that, by now, the FAA would've phased out most if not all their NDBs in favour of VOR and Localiser type NPAs.
It looks like you need more up to date input than I can provide.