How do you value bet the river?

[Pokey]

Lately I've been adjusting my game to try and squeeze more EV out of my winning hands. I've heard the advice from other players that our opponents are nimrods and we can always value-bet for more than we think. The conclusion was that we should bet more than is "reasonable" to call, knowing that they'll call often enough to make it worth our while.

I question that wisdom.

I used to value bet the river for 2/3rds of the pot when I had a great hand. Sometimes my opponents would fold, yes, but when they called I made quite the bonanza. Everything seemed right with the world, but my winrate at showdown was lower than I preferred and my winrate in PTBB/100 wasn't where I wanted it to be.

I've changed my gears lately, to good success. These days, I'm betting about 1/2-pot or slightly less at the river when I've got a good hand. My results have been very strong for a few different reasons:

1. A smaller bet is easier to call. As a result, the strength of the average calling hand is lower, meaning that I win more often when called. A big bet that is ONLY called by a hand that beats you is not necessarily a better bet than a small bet that can be called by hands that you beat.

2. With a REALLY great hand, you often have the deck so crippled that your opponents can't have much. A big bet folds them out almost every time, whereas a small bet might get more "meh, maybe he's bluffing and my QQ holds up" crying calls.

3. Ignorant, unattentive, and aggressive opponents can misinterpret a modest bet as weak, and come over the top on you, even though they would have folded to a solid bet. This is an EXTREMELY +EV thing to have happen to you.

4. When your opponent has absolutely nothing on the river, he will often fold to ANY bet. Making smaller value bets means that your river bluffs can be smaller in size; that means that your bluffs don't have to succeed nearly as often for them to be profitable for you. Example: if your river bets and river bluffs are both 2/3-pot, your opponent must fold 40% of the time for the bluff to be profitable. If your river bets and river bluffs are both 1/3-pot, your opponent only needs to fold 25% of the time for the bluff to be profitable.

Obviously, I'll vary the size of my bet based on my opponent and the board -- if my opponent goes to town with garbage, I'm comfortable value-betting larger, but if he's relatively tight then those smaller river bets really pay off in the long run.

I'm very curious to hear other people's thoughts on the subject.