In Cixin Liu's Trisolaris novel trilogy, in particular in the second book "The Dark Forest", a small number of humans acts as so-called "wallfacers". They are supposed to devise a (hopefully) failsafe plan to thwart an upcoming attack on Earth. The truth about this plan is kept exclusively in their minds and thus safely away from otherwise omnipresent surveillance by the adversary; wallfacers may (and even should) completely mislead the general public about their intentions.
In an effort to counter this, the adversary assigns a "wallbreaker" to each of the wallfacers. The wallbreakers' mission is to find out the actual plan of their respective wallfacer ... and confront them with whatvthey have deduced.
In so far (just reading the third one of these events) all of these cases, the wallfacer who has been confronted by their wallbreaker is implied to have failed. I do not understand why.
Suppose a wallfacer has devised a plan in secret. Once confronted by their wallbreaker (which, I think, does not even have to happen in public!?), the wallfacer typically admits the wallbreaker was right. While I fail to see the necessity for that part already (couldn't the wallfacer just keep denying everything, or pretend they have successfully mislead the wallbreaker?), why is it that the wallfacer wouldn't start working on a new plan? They came up with an idea once, who's to say they cannot do it again?
Note 1: As mentioned above, I am still reading the novels. An explanation might follow later in the book. Yet, the way the described sequence of events appears to be presented as the invariable logical way of things to go is really confusing me and diminishing my enjoyment of the books as I cannot follow the author's logic.
Note 2: I have deliberately been very brief and superficial in my summary of what happens in order to not take away the suspense for visitors who would still like to start reading the books.