u/Grouchy_Spot_6640

In Part 6, Pucci plans to recreate the universe under the effects of "Heaven", Heaven meaning that everyone is aware of the flow of fate and what will happen to them in the future. It was his hope that, with the complete removal of uncertainty, people would live without anxiety and achieve some kind of enlightenment or evolution.

We see what Heaven is like at the end of the part, but I think that was a sort of "incomplete" heaven, since the universe was only partway done. In that universe, people wake up at the point in time Pucci chose, and it seems as though the Heaven effect only starts there, as they act as it's a new thing.

I think what a full Heaven effect looks like can be seen in Diavolo, more specifically Epitaph.
Epitaph let Diavolo see into an absolute, unchangeable future. And it drove him insane.

He constantly checked Epitaph because he was paranoid about the future, and what he saw confirmed his paranoia and drove him into a horrific spiral where he did everything he can to destroy his fears and anxieties. I think a universe where everyone has to deal with their inevitable fates will create a universe full of people who want to avoid that fate.

Or something idk.