People should talk more about how Arya is explicitly stated to be really good at managing finances.
•She’s incredibly good at math and running a household.
•She has seen the horrors wrought by a ruler who begggers the relm.
•She has no taste for the lavish and expensive events that drained away the capitals gold.
•She even speaks the language if the Iron Bank for Petesake.
I guess the point is that when Arya is queen, she won’t even need to appoint a master of coin.