I used to have an instructor for IMCR. An ATPL (or so he claimed).
One day I asked him: if you were flying an NDB IAP and the ADF was saying you are OK, but a handheld GPS was telling you that you are about to die, what would you do?
His reply: I would trust the ADF.
His reply is correct according to the rules, of course. But there is a 99.999% chance he will be dead.
Actually, his reply is a load of bo11ocks in any private flying context, because no law stipulates what equipment is to be used. Only equipment carriage is specified. In CAT operations this is different, but he would still have been just as dead.