Part: Part Six - Betting After the Flop

A lead with a reason

Flop
Heads-upPot 1,300 (6.5 BB)7♠8♦9♣BB6♠5♠● 25,000 (125 BB)YOUthe nuts on a board that smashes youBTN● 25,000 (125 BB)Button (PFR)yet to actD

You defended the big blind with 6♠5♠ against a button raise. Flop 7♠ 8♦ 9♣ - you flop the nut straight on a board that hits your range far more than the raiser's.

You flop the nuts on a board that favors your range. Best?

WhyLead into him. Normally you check to the pre-flop raiser, but this board smashes a big-blind calling range (connectors, suited gappers) and misses much of his. Leading builds a pot with the nuts on a board where he won't c-bet often, and you can keep firing. A lead needs a reason - here, the board, is it.
What happensYou lead 800; he raises with two pair, and the chips go in - your straight is the nuts.  You win a big pot.
You broke the usual 'check to the raiser' rule because the board belonged to your range and you held the nuts - a donk-lead with a clear, specific reason.

Donk-leading is usually wrong, but correct when the board strongly favors your range and theirs misses - lead with a reason, not out of habit.