Earlier quoted context omitted.
The way I see it there are at least two possible ways to "fight" against this, that is if you're on the liar's side. The first one is to offer to whoever is questioning you a "local maximum" victory, i.e. to pretend to hide a smaller lie compared to the bigger one you're supposed to be hiding. In the case you mentioned, you could pretend to be "covering up" the fact that you've been cheating on your SO, hence all the…
> The second strategy is to be so good at this as to believe in your lies/stories you're telling. That is harder than it sounds. Even sociopaths have a hard time outright lying. Or keeping lies straight. The technique being used here is one of consistency . Is your story consistent? Does it have all of the details one expects from a normal story? Are there any hesitations when recalling the story? It is very difficul…
Do all your imagining ahead of time. Walk through and construct the lie. Fill in the details. You're not just imagining this one thing, you're imagining an entire alternate reality where this thing is true and all the implications that follow from that.
When it comes time to answer questions the person is asking about the alternate reality you've imagined. No need to make things up - just recall back.
I guess I'm saying the same thing as you, just in a different way - don't make something up on a moments notice, just have a different story that you tell.