[Guruman]

I think you have to threebet sometimes when you have a vulnerable made hand on the flop.

ex:folded to an agg sb who raises and you defend with K7o. The flop comes 573 rainbow.

check, you bet, villain raises. You should probably reraise here. You hand is very vulnerable to high cards falling, and you're not likely to improve much. Villain may call you down with an ace or worse seven even after the threebet, in which case the raise was clearly the correct move.

If he check/folds the turn then you can threebet the flop with your good draws and high overcards HU with him in the future.