In Twilight Princess, you can't open a treasure chest with a rupee worth more than 10 rupees in it if that rupee doesn't fit in your wallet. For that reason, it might be more desireable to have a smaller amount of money so that you won't be unable to open a treasure chest with money so that you will have more money later. There are many ways to reduce the amount of money you have; making a purchase, donating to the bird in Northern Faron Woods, and donating more money than you need to to the bridge repair and Castle Town Malo Mart. You can also postpone giving Agita a bug so that you will be able to open a treasure chest with money and give her that bug after you open that chest. You can also purposely give her a bug when you have a full wallet instead of later after you spend some of it so that you will have less money after that purchase so that you will be able to open a treasure chest with money. After you get the magic armor, it's much easier to get rid of money.