Open raise sizing
In the past, players believed that they should open larger sizes from early positions and smaller from later positions because they have a stronger range from early positions.
But with the implementation of solvers, a completely new theory was developed where the matter is completely reversed, and we open small sizings from early positions and larger ones from late positions. Why is that so?
For the simple reason that most players in cash games, which involve rake, will use a 3-bet or fold strategy because they have a tight range and will face a smaller amount of aggression, i.e., they will not be squeezed as in the case of calling.
This way, early positions with smaller sizing lose less against 3-bet and can still 4-bet their "nut" hands.
Similarly, from later positions, we can expect more calls and fewer 3-bets and risk less opening/folding with higher sizing.
Depending on the sizing and profile of our opponents or the player pool, we have to adjust our strategy to gain EV instead of losing EV with our marginal hands.
If our ranges are adjusted to playing against a 2.5x open from all positions, and we are faced with a 2.2x or 2x open, our adjustment should be to defend with a call or 3-bet wider than usual.
If we open a specific range from the Button and see that our opponent on the BB is defending 10% less than optimal, our adjustment should be to start opening 10% more hands and thus get more folds.
Likewise, if our opponent defends his BB vs. BTN much wider than expected, we need to adjust so that we open fewer hands and go for value with our strong hands, whereas post-flop, we will get calls from his marginal hands.
Also, increasing our sizing brings more EV to our premium hands.
The same thing applies to defending against a 3-bet; if the 3-bet is of a smaller size, we will defend wider than our usual range and vice versa.
Likewise, against narrower 3-bet ranges, it is necessary to have more non-dominated hands in the range and more small pairs and suited connectors with which we can have good implied odds.
Things change if there is an ante in the pot or, more recently, "splash the pot" where 10 or 20 big blinds are added, of course in these situations, we will have to be wider and play much more aggressively due to the simple fact that from the beginning of the hand, we have premium pot odds.
Another interesting concept we came across is Time EV, i.e., instead of looking at our win rate through bb/100, we can look at it as bb/hour.
For example, in our range, many hands bring us 0 EV and serve only for the benefit of balancing the range; they do not bring anything to our winrate but just take our time.
Therefore, preflop, we can fold 0 EV hands in fast fold games (especially anonymous ones) and thus optimize our bb/hour.
Otherwise, we should be careful with this concept because by throwing our bluffs out of range, our opponents can adapt and defend less and reduce the EV of our value hands.
That's why if we play lower limits against worse opponents who won't exploit this concept, we can increase our bb/hour.