Well when you are able to see the future and determine the end and have access to computers that can game out every single possible event in between with alternative moves and counter moves for years, Nana is thinking that is just a little bit easier to do.
The beauty of it to me is the timeline manipulation that was achieved pretty much on target on both sides that forced the evils to expose their OWN dirty deeds one right after another over and over as tho they were incapable of stepping out of their rituals was the genius of it.
Q literally used their own rules to destroy them. The same rules and rituals they have used against us for centuries.