Normally the problem has each person having a different problem (to draw our the most knowledge from us) so that’s why parties is usually the better approach.
But once you do your planning you can tell if actually lots of people have the same issue so can group.
I often said to others if it seems that 2 people have the same issue, look again as it’s often not. Ie in company law, conflict of interest, one director took a deal meant for his company and did it himself. So conflict.
But another was told of a deal on a racehorse when on a company visit. That’s not a conflict (company had nothing to do with horse racing, it’s similar to just being told by a friend to invest in Bitcoin etc).
So 2 different results but lots of people just lumped them together as the same thing.
But always ask yourself why would the examiner chose to do that?