How can you decide which play win more games, more gammons? Are you computer :) Do you memorize some reference positions and compare them, or is it just about experience?
It's not nearly as hard as I think you're making it out to be. Take an example:
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| XGID=a--BBBBbB---dC-A-c-e--A---:1:-1:1:63:2:2:0:5:10 | |||||
| Blue to play 63 | |||||
OtB 22/13 was played. Between it and 15/6 which play wins more gammons? Clearly 15/6 because our plan is to attack when our opponent has no developed forward position and gammons are lurking all over the place if we complete the close out. Which play wins more games? I think that should be running out but it won't be by much because again, a great game plan here is just to finish him off. Which play loses more gammons? There's certainly not much of a difference here though I'd give an ever so slight edge to 15/6 losing more gammons.
So we have 15/6 winning a lot more gammons and the other two parts of the equation in favor of 22/13 but I expect there isn't much of a difference in either of them. Now just weigh out if you feel the little bit of extra gammons lost and the slight amount of extra single wins can compensate for the massive amount of extra gammons won. Sure doesn't seem like it, so 15/6 it is.
Stick