how to avoid overextending when the opponent plays passively ?

"+0,8 , +1,2 is the difference between drawing and winning"

• Yes, the threshold is +1.
  From a theoretical point of view, like ICCF correspondence white will win +1.2 and black will draw +0.8.
  However, in practical play white has to be precise to convert +1.2 and black has to be precise to hold +0.8.

knight can take f6 option

@tpr said ^

"+0,8 , +1,2 is the difference between drawing and winning"

• Yes, the threshold is +1.
  From a theoretical point of view, like ICCF correspondence white will win +1.2 and black will draw +0.8.
  However, in practical play white has to be precise to convert +1.2 and black has to be precise to hold +0.8.

"ICCF Correspondence" is equivalent to "Engine Chess" at it's best at the time the game was played. It's rare ICCF players do not engine consult, unless they are experimenting with openings or such, or un non-rated games.

Also, such mathematical equivalents don't mean much in practical play. OTB players do not talk in those terms. More broader terms like "slightly better", "stands better", "decisive advantage", or "equal" are more likely to be heard in chess conversations. "I had a .3 pawn advantage here" is a dead givaway to someone who is way too engine-reliant, and is not the way you play chess, or even talk about it. This from my own OTB experience.