From No Limit Hold 'em: Theory and Practice by David Sklansky and Ed Miller.
Concept No. 32: It can be correct to fold a hand before the river that has a better than 50 percent chance of being the best hand.
This is certainly true, but there are two reasons that each would be sufficient even in the absence of the other. Sklansky and Miller ignore the first of these reasons in their discussion, and only touch on part of the second.
1. It matters how far behind you are when behind, and how far ahead when ahead. For example, TT is ahead 4/7 of the time against a range of AA,KK, or AK, but it only wins about 40% of the time. This is because it is way behind 3/7 of the time and only a little bit ahead 4/7 of the time.
2. With more cards and more betting still to come, other factors come into play when it comes to EV. Your pot equity can take a back seat to the power of having more information about your opponent's hand than he has about yours. The obvious example is that if you are out of position, you will have to act first in later rounds, and thus you will give your opponent information about your hand before each of his actions. Also, if you are a tight player, your opponent will have a better idea of what sort of hand you are likely to be holding. Furthermore, drawing hands have an information advantage on later streets; whether the draw is hit or missed, the player who was drawing can be fairly certain of whether he has the best hand or the worst hand. All of these factors are more important in NL holdem than in Limit, because players can make larger bets after accumulating the new information.
Sklansky and Malmuth are right about this concept, but their analysis neglects all these factors except that position becomes more important in NL, and that "vulnerable" hands (ie, moderately strong hands that can lose to many draws) lose some value in NL.
Concept No. 33: Be willing to risk free cards to manage the pot size and induce bluffs.
This is good advice. With certain types of hands (in particular, "vulnerable" hands), you would prefer to play a small pot. I've never had much use for the concept of "pot control" or "managing pot size," but it's not really such a bad way to conceptualize why it's best not to bet with certain moderately strong hands. I'm not in the habit of using these ideas; I always just think about it in terms of managing my range and trying to maximize my EV. If I bet with a medium-strength hand on a drawish flop, I will tend to be called mostly by better hands than mine or draws; I will lose a lot against the stronger hands, but gain only a little against the draws. Making matters worse, players holding draws will sometimes raise as a bluff, forcing me to fold. If I do decide to bet the flop despite all these dangers, I will probably check on the turn, regardless of whether the draw comes in. If I bet, I will have problems similar to those I had on the flop, only worse. I will have shown strength by betting, but my hand will be among the weakest in my betting range, and I will have to consider folding if there is a substantial bet on the river. If instead I check and show weakness, my hand will be among the strongest in my checking range, and I can pick off lots of bluffs on the next street.
There is way too much information to process exhaustively at a poker table. Even when I sit at home and analyze hands, I often have to generalize and guess at EV in certain situations, because it's just too complicated to approach it more thoroughly. So, it's necessary to conceptualize poker and use principles or heuristics to simplify decisions. The way I think about the game lends itself much better to the EV and hand ranges conceptualization, but there is value in using a higher-level conceptualization such as pot control and bluff-inducing, as Sklansky and Miller recommend. In future analyses, I might try occasionally to approach problems with both conceptualizations if I think there is a chance they will be at odds.