Hmmm... something about young new players and an 11th level finale showdown does not compute - to me at least.This was a bunch of young, new players. I am the experienced one in the group. So I really think it is my own fault (and the adventure designers). And they were sealed in a dungeon for a long time and couldn't just leave to get new items.
And now that I think of it the rogue did have an item that let her summon animals. She summoned a few giant birds and flew the barbarian across. Which was when I decided it was a good excuse for the BBEG to teleport to the other side and summon a whole bunch of minions. The birds flew the barbarian back so he could get back in the fight.
One would have to start expecting at some point during the 5th to 11th level progression a normal variety of challenges would have led to even a little savvy on how to get around a gap.
While I am **not** a die hard start at first type, one does need to let the gradual level and play show folks a bit of the ins and outs.
Just like with mystery novels the more one jumps to the end, the more you lose out.