In reality.
His main cultivation was the Inner Strength scripture "Lu Wu Demon Cleansing Scripture," and during his Grandmaster limit stage, he was already close to the thirteenth layer. Not willing to waste his Qi-Blood, he deliberately slowed his cultivation progress.
After becoming Great Grandmaster, breaking the Qi-Blood shackle, his Qi-Blood upper limit soared to ninety thousand. With no such concerns, he let loose with cultivation; thus, in just a year of seclusion, he broke through to Middle Realm.
Qi-Blood, breaks through thirty thousand!
This is truly a case of a long accumulation erupting in one move.
Of course, such a situation is rare. Under normal circumstances, even for him, going from Initial Realm to Middle Realm in Qi-Blood cultivation, even within a Grotto Heaven, would take about two to three years.
