Okay, so I went away again, and thought about this even more. That stuff up there, the me thinking out loud, is a weird, and I think wrong way of looking at it. There's a much simpler way of looking at things.

Assume heads up flops, against villains who play straightforwardly, and that you have excellent reads on.

If your equity when getting called is greater than 50%, cbet for value.
Otherwise, if your equity against villains current range is less than you make from cbetting, cbet as a bluff.
Otherwise, check.

I think this is it in it's purest form. Is it correct?

There are other factors that come in, of course. Money made from turn barreling, for one. Implied odds from catching up when the pot is bigger, would be another. Yet another is being uncertain of your opponents play, and avoiding difficult decisions on latter streets.

This last one - the risk of being outplayed, or of making missteps against players who play erratically - I think is why it's best for beginners to just fire away, take the pot down, and avoid getting into complicated situations on latter streets. It might also be good idea for better players against unknowns. A little money is better than none, and better still than a loss. However, once we get some experience under our belts, and our confidence in making very accurate decisions on latter streets increases, I believe we can check for value.

Here's how I came to this realization.

There are 3 cards on the flop, and the pot is $100. Villain has {a range}, and checks to hero, who has {a hand}. Hero has 50% equity against villains range. If hero bets $70, villain will fold 50% of the time. When villain calls, hero is drawing dead. Betting yields a profit of $15 dollars. If hero checks behind, villain will only put money in on latter streets if hero is drawing dead, and hero will make a good fold. By checking, hero wins the $100 pot 50% of the time, and so checking yields a $50 profit. More the 3 times the amount hero would have made from cbetting.

This is grossly simplified. We are rarely drawing dead. Even though we're behind if he calls our cbet, we have some equity, and so will make more than the automatic $15. Also, sometimes villain will bluff us out latter, and we'll make a bad fold, or could improve, put more money in, and still loose, so the $50 figure is probably lower (it could be higher though), but $15 has to increase alot, and $50 has to decrease a lot, before the first is greater than the second.

So often times, against easy to play opponents, when one has a marginal hand, it's best to check behind, than to take the smaller immediate cbet profit.

Is this basically it?