I'm kind of amazed that anyone has ever found a runway using an NDB approach. It's just simple arithmetic - if you take a classic NDB approach with an NDB say 5 miles off the end of the runway, used first as an IAF, then a procedure turn then as the FAF with a 5 mile segment post-NDB. Let's say that your compass is accurate to 1 degree (trying not to laugh here) and you can fly to an accuracy of 1 degree also. Then the mean error is about 1 degree. So 5 miles from the NDB, your mean misalignment with the runway is about 5*6080*(1/57) - about 500 feet. Now use realistic compass accuracy and flying skill and you'll be lucky if you're within 1000 feet.
Actually on my IR checkride I flew an NDB (there were still some back then) and DID have the runway on the nose. I was quite pleased with myself, but it's pure luck.