Check this out and it will answer most of your questions http://wizardofodds.com/games/video-poker/strategy/double-bonus/10-7/
damn, I always keep the single face card. My logic is: with a single face card, any one of the three other cards will give you a winning hand; with a small pair, you need one of the two remaining cards to get a winning hand.
Or any other pair. And then there is the added ease of making a full house or quads. But the real issue is trying to think better than a computer. There is a Strategy chart on that site I listed. Just scroll down, print it out, and follow it when you play. If you are going to play Double Bonus the strategy is all counter intuitive. Computer tutoring software is not too expensive and will give you fun bits to try and entertain you at home while sharpening your game for the casinos. You can change pay tables on those tutors (which alters strategy) You can set them up just to practice certain hands by choosing one or two cards to always appear. This is a good way to practice playing hands with Aces or K-Q hands where the strategy is often counter intuitive. Double Bonus gives back more than 100% with perfect strategy, so the casino needs folks who try to reason out the play, and so make errors, or they just alter the pay table to give them the advantage. There are a few around. I like the one that Dean Zamzow created (and then Dancer put his name on) and I order it right from the creator so I get good service afterwards. https://www.zamzone.com/ There is a demo you can try on that site to see if it is something you'd like.
With DDB you're really just trying for 4 of a kinds, pairing up that high card doesn't win you anything(just a push)
When my gf first started out, this was easily her biggest mistake. And she would mostly only do it when there were two high cards. But a pair is much stronger than either of these scenarios in any vp game. You are forgetting it's much easier to make two pair in JoB when holding a pair, or quads in DDB when holding a pair. In most non-wild games a low pair is roughly worth 70-80% of your wager. A single high card is only worth 40-50%. It's a pretty common scenario too, picking the high card every time will cost you a LOT in return. My offhand guess is it would turn a 9/6 game (99%) into a 6/5 game (95%). Edit: Worse than I thought. Any high card over a pair and ignoring 3 card SF draws vs. high offsuit cards makes 9/6 JoB a 92.3% game. Holding 2 high cards in favor of a pair knocks the game down to about 95.96%
The correct play weighs the payout vs the probability of hitting it. That's why you see different strategies for different games.
When you make your decisions according to what seems logical to you, you won't consider every possibility and you'll give too much weight to a few possibilities. You need to learn the paytables and the strategies to have the best chance at video poker.
But holding A10s instead of the lone ace in JoB/BP is always the correct play (to hit a Royal, that is, haha)