Inside straights: usually no, sometimes yes

An inside straight is missing a card in the middle: 9-J-Q-K needs a ten and nothing else. Only four cards in the deck fill it, half as many as an open-ended draw, and that one difference is what makes four to an inside straight a losing hold nearly every time.

Draw to it in one case: when at least three of the four cards are high cards. Then you are not really drawing to the straight alone — each of those high cards can pair up and pay on its own, and that extra value is what tips it over. With exactly three high cards there is one catch: if two of them are the same suit, keep just those two instead, the way lesson 7 says: 9♦ J♥ Q♥ K♣ 3♦ is a hold on J♥ Q♥, worth 0.60 coins per coin bet against 0.53 for the four-card draw. (Three of the same suit is three to a royal, lesson 6's hold, and worth far more than either.) J-Q-K-A is the exception to the catch — with all four cards high the draw is worth 0.60, and it beats any suited pair among them except Q-J. So A♠ K♠ Q♦ J♣ 3♥ is a hold on all four, 0.60 against 0.57 for A♠ K♠, while Q♠ J♠ A♦ K♣ 3♥ is a hold on Q♠ J♠, which edges the draw by a hair.

Example: 9♦ J♠ Q♥ K♣ 3♦. Hold all four. 9♦ J♠ Q♥ K♣ returns about 0.53 coins per coin bet, against 0.50 for J♠ Q♥ K♣ on their own.

Anything less and you let it go. With two high cards, keep just the high cards: 9♦ T♠ Q♥ K♣ 3♦ is a hold on Q♥ K♣, 0.48 against 0.47 for the draw. With one high card, keep that card alone. And with no high card at all the inside draw is worse than starting over — 5♦ 6♠ 7♥ 9♣ 2♦ is worth 0.34 held and 0.36 if you throw all five away.