If the game keeps with KH's tradition of final bosses, this one probably has multiple phases and I hope they go all out. Perhaps there are more save points in between multiple sets of bosses. The only thing I can think of is that Scala is literally one, massive set of boss battles to the point that some players wouldn't be able to complete it one sitting, hence the need for dedicated save points. It would be similar to "End of the World", just with more bosses and less corridors.
This would explain why the leaker can't show much of anything, the entire world is the final showdown (one giant spoiler) with Xehanort and perhaps all his other selves as soon as you walk a few steps forward. Rather than having more corridors, you have multiple phases with some of the Xehanorts, a corridor of random enemies followed by a save spot, then another set of bosses, rinse and repeat until you make it to the top (Tower of Endings) for the final showdown with Xehanort, which I hope contains a phase that transitions into the true Kingdom Hearts for the final phases. The leaker previously said there are no scripted sequences like cutting buildings in KH2, which makes me think you have options or "can do anything".
So it seems you can't walk/explore much because it will trigger another sequence of bosses.
Perhaps this is just wishful thinking, but I would love that.