So PIO can use basically any sizing and get roughly the same value even if gave jam or check, I'd get a value that was close to the original EV. It'd be less but not by a huge amount. The 10% sizing, I think is trying to take advantage of player who thinks that they can call lots of hands preflop and then play tight passive postflop to realize their EV. At 10% pot, it's not terribly lucrative to outdraw your opponent and you're forced to raise regions that aren't normally raises so it could be a good exploit, but it's not the holy grail of 4-bet pot play or anything.

On the always call idea, it's something that I think PIO uses more effectively than a human can, just because it has perfect information on the opponents strategy, hand ranges and betsizings, so it can leverage small mistakes in range construction into nice EV gains. In practice, I find that as the caller it's easier to make mistakes, because no-limit is mainly about geometric growth (stronger hands = bigger pots), but in a 4-bet pot, the pot is basically the maximum size going into the flop, so it becomes more like a limit game where it's about not overfolding and calling many low equity hands for stacks. It'd be a big mistake to consistently stack a 50% equity hand against hand range with a SPR of 20 (think A8 on 732). In a 4-bet pot these type of calls become mandatory think 80% turn call then another 80% river call.

5-betting always depends on ranges at 200bbs deep, we can develop a 5-bet fold region and he can develop a 5-bet call region (roughly similar to the 4-bet call region against the same range). In general these ranges are going to be tight, because the 4-bet ranges rarely exceed 5% of hands and we can generally 5-bet roughly 50% of original range or 2.5% of hands and of those 2.5% we have to stack roughly 50% (1.2% of hands) so basically most 5-bet/call 6-bet situations are going to be AA + a mix of AKs, KK. The mix is important because of the blocker effects of suited As on the region, so without calling some AKs and KK, any random suited ace becomes a profitable 6-bet. If we always just call KK, but not AKs, we can run across range constructions like (AA, A5s) where KK only has 37% equity (not a profitable call), but AKs has 40% equity (becomes a profitable call). On the same token if we only call AA, AKs, then 88 actually is very close to a profitable 6-bet bluff jam.

I could be way off, there is that yellow font top right that shows BTN vs CO 4BP entire video that is completely throwing off ranges in my head. The RIO title makes sense for MP vs CO in terms of ranges used with the AQo being folded, mixing TT, etc.

Also are you using "Natty" as just a close spot? I don't hear that word very often but used it multiple times with some small EV bluff catchers like KQh on Q652sss facing a double barrel.

Yeah, I mislabeled the sim. It's MP vs CO. Natty -- is slang for dislikable.

I like the sizing idea, but I think more practically ranges are going to be weaker going into the triple check line than the double check line because some value hands from OOP are going to bet river to cover the odd ball bluff. So PIO I think is protecting against putting too much betting volume in on the triple check line, but I don't know if this a reasonable consideration considering how rare this is. I think in practice in happens less than 1% of the time in a 4-bet pot-call spot or I think approximately 1 in every 500,000 hands or so of 6-max for these specific positions

Okay so I agree with you completely with one qualification "If I was playing PIO, then this would be true".

The main struggle I have with the argument is TT performs substantially better against any blunder from my opponent. If he 4-bets 99 or A9s or 98s, TT instantly becomes more valuable than 88, so in these situations where we're playing some guy with a 5 o'clock shadow whose been grinding all day -- I'm going to take TT over 88, because any mistake he makes TT is likely to capture more EV.

Yeah, it's not really no-limit in the classic sense, because we already put in all the money preflop :).

Yes, you can find range constructions where your opponent simply can't bluff enough so we can fold hands in and below his bluffing range. Sometimes you'll see this against a player who likes to call pocket pairs + suited connectors to 4-bets on like a 953 with an Ace turn.

I've modeled this a couple of different ways and KsQs is jammed between 0% and 70% depending on the betsizing parameters -- My guess is that it fits KsQs here, but no value range really benefits so PIO generally is just avoiding it or trying to fit hands like QQ, AJs (At frequency) into the jam range with KsQs.

OOP it's probably fine -- though as ranges get wider (10-20% 3-bet), flatting will have some value. IP every model, I've ever seen along with my experience/database analysis indicates you have to flat and use your positional advantage.

I think the main reason why you don't see it much is that the value of the mistake 4-bet is going to be far worsen that the value of a mistaken call and 3-betting ranges don't converge terribly quickly -- the difference between 4-bet vs 6%, 8% and 10% is quite large and over most samples these 3-bet numbers are indistinguishable from each over.