I also hesitate to add my thoughts, but this thread totally resonated with me. I have used tarot cards to answer yes/no questions, both with the training deck and one without yes/no printed on them - the answers were the same.
I think the issue is that we are humans and have differing opinions, which is why there is no universal list of which cards are yes, no or even maybe. I think perhaps it could be one of those things which is between the deck and the Reader? As has been pointed out, some decks might not ‘do’ yes/no questions so well, whereas others might - not to mention, if the Reader isn’t entirely certain on what is yes or no then the deck probably won’t be either, any result could be questionable, perhaps? I think like with any divination tool, it requires a connection with the deck, trust in one’s intuition and ability, and an understanding between the 2 - agreeing with your deck what you consider to be a yes card and no card might be a good place to start? Also, deciding whether or not you will have a ‘maybe/unknown’ as answers too? I hate math, but if you wanted to get technical about it, there are 78 cards in the deck, so if you wanted to separate them into 3 sections, say yes, no and maybe cards, then you could do that and that would be your understanding between you and your deck.
In addition to using the 1 card method, I’ve also tried the 3 card method - pull 3 cards, if 2 or more cards are higher (or more positive), that could indicate yes, 2 or more low number (or less positive cards) could be no, and an even-looking spread is maybe. In the same way, you could agree with your deck that major arcana cards are yes, court cards are maybe and numbers are no; there are more numbered cards than any other group, so by making numbers no you’re making it (possibly) less likely to get a yes, which will be validating if you do in fact get a court card. Or, separate them (in the agreement) into major arcana, wands, cups, suits and swords to have 5 options; so you could assign a yes, no, maybe, ask later and let it go, for example.
I also prefer to double-check my results, to prove to myself that I’ve got the answer I was supposed to get; if the answers don’t match, I know that I need further insight into the situation.
x Blessed Be x