But in book six, everyone got yanked back to the set story she had for them when, IMO, she should have just been like "okay, let me just see where *they* take *me*" instead.

This is a very interesting insight, and, IMO, probably accurate at that.

I would now like a round trip ticket to the alternate universe in which JKR did decide to see where they took her, and appropriate clearance to bring back that universe's book six and seven (and any others that might hypothetically have come after).