Dragon Hand- if you know one card

Once playing Pai Gow there was an option of taking a second hand, called the 'dragon hand' if the table was not full. The dealer was flamboyant and it was more often than not easy to see one card of the dragon hand before deciding if you wanted to play that hand. I would take it if I saw an ace/king/joker, and decline on all other cards.
Was my strategy proper, and assuming I could always see the card, and was the only player taking rthe optional hand, how much would this tip the odds in my favor? Thanks for any info.

It's impossible to quantify this accurately, because the decision should also be made based on the cards in your hand. For instance, if you had three Aces in your original hand, seeing the remaining Ace or Joker in the dragon hand would be very powerful, and make that hand worth taking.

I have a particular heuristic for taking the dragon hand, and that is that I always take it if I have two pair, AND I've seen that someone else has two pair. That's because for every two pair dealt, the likelihood that any other given hand will also have two pair rises by 20%. The key factor is, the house way very often misplays two pair, plus, I can play my hand knowing that there is an increased likelihood that the dealer will have two pair. (I realize that the above doesn't directly impact your question, but if I had two pair and the card I saw in the dragon hand was, say, 10 or higher, I think that would tip me over into taking that hand.)

Since you have to overcome a 2+% advantage, and the card you will see is, after all, only 1/7 of the hand, I would want that card to be an Ace or Joker before taking the dragon hand. A King probably wouldn't be enough to overcome the house advantage, and if this situation was recurring on every hand, I wouldn't have that much incentive to grab the King hand anyway.