In "The Magicians", Quentin is back on Earth after having caught The Questing Beast. We learn (on page 377) that he feels that ...
... The spells involved in retrieving cash from an ATM were child's play now.
But in "The Magician King" (page 107) he relies on Julia to extract money from an ATM
Julia showed [Quentin] how to extract cash without a card from an ATM [...].
Quentin should have been easily able to cast this spell himself, so why did he need Julia to extract cash from the ATM in "The Magician King"? Is there a good explanation somewhere?