Time passed as the cultivation session continued...
The good thing about not being in the Golden Palace anymore was that the twins' group didn't have to worry about a time limit. Back then, they would use one fruit every three months of cultivation, but the way they cultivated there was extremely wasteful. Not even 20% of the fruit's energy was added to their cultivation in the end.
It couldn't be helped, since they had to make the most of it before the palace closed. Eventually, they found out how to acquire the fruits from the Astral Tree, and now they are back in the Divine Realm.