Mine are all people but there is a lot of variation within that. Some are naturally lit, some are studio lit and some are location lit. So there is a bit of skill required in being able to manage all three. There was one submission that passsed with a whole set of studio shots, but the variation there came from low key, high key, head shot, 3/4, full length. Variation need not be about subject variation. There was also a set of 10 flower pics and it almost passed but the last three images fell short so it failed, but it failed on the dip in quality in the last three images, not because of a lack of variation.
It's those things that you would pick up on my attending and I would definately encourage you to do so, there is only so much you can learn from the handbook and forums. Seeing it and hearing the feedback is well worth it and I consider myself extremely fortunate to have passed without doing that.