This comes about mainly because, as I understand it (I have never flown in the land of the free) you do not fly NDB procedures on test in the US. In the UK you currently have to fly a single engine NDB hold and a single engine NDB approach, no quarter given! Hope this helps.
I flew one on my test, I think if i remeber right that you have to fly 2 non-precision approcahes from VOR, NDB, GPS, LOC, LDA and SDF and one precision approach. So I guess its down to the examiner if you fly one and also the approaches avaliable in the area you are taking your test.
J.