Wu Long needed a lot of time to thoroughly make sure the ritual worked and that it worked in the way he first understood its principles, without harming Helian Muyang.
Thus even after Cai Yin's success on the 6th day of the opening of the Secret Realm, he continued delving into the knowledge that the Vault offered.
Of course, it was too vast to completely examine in the limited time he had, and thus he was primarily targeting the specific parts concerning the ritual of the Extreme Yang Physique's transfer.
On the night of that 6th day, coming up to the very limit of the deadline, barely making it in time, he finally confirmed that it was indeed possible to make that transfer, as well as was now familiar with all the steps of the ritual.
