@Humpleupagus @gav I did read Zarathustra but it's been a bit, definitely the type of book that deserves a re-read. In Zarathustra it's absolutely a thought experiment that relies on the individual's assessment of their life it says everything will happen in your life exactly the same would you love or hate that, no choice involved, which I believe is a key difference.
In the Will to power he talks about it again and admittedly I don't remember the exact passage but some take it as admitting a real belief, however, it seems strange to say it would be the result of will. Will to power is a drive that calls things to action, I don't see how someone could drive recurrence with their own will.
He definitely saw things as recurring though, especially with his analysis of nations and politics so it wouldn't surprise me if his views evolved on that and I'm just missing a key detail.