Anyone can fix a mistake.
In the spirit of “teach a man to fish,” I think the bigger challenge is to help a section understand why they made that mistake. Teach them to recognize the psychomusical reason why they made it, and they’ll be able to avoid countless future mistakes.
Here are a few common mistakes, the ones I point out most often to my students.
Maybe it’s a leap close to, but not quite an octave. They default to a familiar intervalic leap.
Maybe there is a dissonant vertical interval, and they subconsciously adjust to a consonance. Instead of the tritone written, the basses sing a fifth with the tenors. Instead of the major seventh, they sing an octave.
Maybe there is an interval that looks different than it sounds. Harmonically complex music is full of augmented seconds, diminished thirds, and diminished fourths, for example. Learning to spot these is a game-changer.
That’s to say nothing of, “the rhythm is slightly different at [B] from the same lyrics at [A]” and similar reading challenges.
Taking the time to help students recognize the reasoning takes longer now, but saves so much time later.