JK had hp very well put together, who thinks she does

Um



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She wrote worldwide bestsellers, so...

The structure of the HP books is excellent. At the very end things get rushed, but otherwise everything is well prepared. Most of it pays off in the same year, such as with Ron and his wand in book 2, but the major plot points, such as the return of Voldemort and the confrontation between him and Harry, were both foreshadowed three books earlier than the actual events.

the question is
who thinks she doesn't

When you re-read the books a lot, you notice big things and little things foreshadowed. Such as Mrs Figg and Sirius both mentioned in PS. But yes, she did an amazing job!