Even with a research plan, solving the problem wasn't easy.
The concept of a critical zone had been around for more than a century.
The zones Re (s) < 0 and Re (s) > 1 were solved the earliest as they were the easiest. The regions Re (s) = 0 and Re (s) = 1 took nearly a decade to solve.
The exclusion of these two areas directly led to the proof of the prime number theorem.
In order to dive deep into this topic, Lu Zhou collected a large amount of thesis in this area. He even found electronic versions of Grothendieck's academic works, which were removed by major publishers. He found the original Étale proof method, as well as the theses published by Professor Deligne on Weil's conjecture.
Lu Zhou actually should have read these theses during his PhD, but unfortunately, he was involved in the field of number theory, not algebraic geometry.