@Kampfarsch In this case it's not the mystery that is being withheld, the characters don't know more than the situation than we do, it's how they'll beat her. If we are aware of their plan, then two things can happen: their plan succeed as planned and the impact during the climax is reduced (since we know exactly what they'll do) or more commonly the plan fails and they either improvise the solution (which is kinda hard considering how OP are the opponents) or win by pure chance or external interference (like against the patissiere).
I'm kind of neutral about not knowing the plan, if the author wants them to have a plan of themselves and succeed, it's a compromise to make it happen without removing anything from the climax.
I'm kind of neutral about not knowing the plan, if the author wants them to have a plan of themselves and succeed, it's a compromise to make it happen without removing anything from the climax.