I've had 3 interesting and very similar experiences with holding a set and facing a straight. I'd like some advice regarding this situation.

Sorry I don't have the hand histories but here is very brief synopsis.

1) I raise preflop with JJ, get one caller and 2 of us go to the flop. Flop is 678 rainbow. I bet 3/4 of the pot, get a quick call. J comes on the turn. I bet 3/4 pot, get raised. I call. 9 comes on the river. I check Opponent bets half the pot.

2)I limp with 66, 4 people see the flop. Flop is 4TK rainbow. I check, opponents check. Turn is a 6. I bet the pot, and one opponent calls. River is a 9. I bet the pot opponent raises all in (he has me covered by only a little bit). He either slow played a set or has the QJ. I decide he's bluffing a missed straight.

3)I limp with 77, 4 people go to the flop. Flop comes 457 rainbow. One person bets half the pot. I raise it to pot sized and get one caller (original better folds). Turn comes 6. I check, opponent checks. River is a 9. I bet opponent raises.

Results below in white

1)I call. I win with trip jacks over trip 8s
2)I call. Opponent had QJ for the rivered straight
3)I call. Opponent had 68 for a flopped straight.


If you read the results you see that I couldn't lay down the trips. Based on my 3 hands, seems like I made some hugely -EV by not folding the set(in fact it was pretty donktastic to make the call), especially in example 1 and 2 where there are 4 cards to the straight.

Thoughts?