so i came up with a theorem of sorts. it's slightly convoluted, but it goes something like this:
i posit that
when a decent or good player insta-checks to you on the river, they are planning to either a) snap off almost any bet, or b) fold to almost any bet. even though these are opposites, this polarization is really helpful. if you have a value hand, bet as much as you can. if you must
bluff, you can get away with making it really small, since you're mostly only pushing out the
hands that completely give up. with A-high i'd lean towards not
bluffing if there's any conceivable whiffed draws that you can beat. obv if they catch on, it doesn't work anymore, but a) this is true for any theory and b) it would take a number of shown down hands in these spots for them to catch on
IME they are usually either checking quickly in complete defeat because they missed their draw or whatever, have almost no SD value, and know there's no point trying to slow you down, or they want to induce you to bet, especially some draw you might've whiffed. marginal hands that really don't want to call another barrel almost always take at least a slight delay before checking, as if they have a decision, to put the fear in you
works best in sizeable pots where at least one reasonable draw missed. i'm sllightly drunk and this might be silly so didn't figure it warranted its own thread or anything
