Part: Part Seven - Betting on Fourth and Fifth Street

An overbet for value

Turn
Heads-upPot 4,000 (20 BB)K♠9♠4♦7♥BTNA♠Q♠● 30,000 (150 BB)YOUthe nut flush drawCO● 30,000 (150 BB)Openerbets 2,600 (13 BB)D

You called pre with A♠Q♠. Flop K♠ 9♠ 4♦ gave you the nut flush draw; the turn 7♥ missed. He bets again.

Nut flush draw, he barrels the turn. Best?

WhyCall. You have nine outs to the nuts plus implied odds against a barreling range - a routine call to draw at the best possible hand.
What happensYou call.  Pot: 9,200 (46 BB).
River
Heads-upPot 9,200 (46 BB)K♠9♠4♦7♥J♠BTNA♠Q♠● 30,000 (150 BB)YOUthe nut flushCO● 30,000 (150 BB)OpenerchecksD

River J♠ - you make the nut flush. Having barreled twice, he now checks.

You have the nuts and his range is strong but capped (he barreled twice). Best?

WhyOverbet for value. He barreled twice, so his range is full of strong one-pair and two-pair hands and sets that can't fold - and because you'd also overbet here as a bluff, your value bet is balanced. When you're polarized with the nuts against a strong, capped range, a bet bigger than the pot extracts the most.
What happensYou overbet 14,000 into 9,200; he calls with a set.  Maximum value.
You drew to the nut flush, and when it came in against an opponent whose barreling range was strong but capped, you overbet for value - the times you can credibly hold the nuts (and bluff) are the times to bet biggest.

Overbet the river for value when you're polarized, hold the nuts, and the opponent's range is strong enough to call - bigger sizing extracts more from his capped strong hands.