While it is true that you could only order up to 5 items at a time in the GameCube version, by saving and quitting and then loading the game back up you could force the game to mail out the items and you'd get them right away. Doing so would empty out the catalog queue, allowing you to order 5 more items. In fact, because of this the GameCube version is actually the only game in the series where you could order as much as you wanted from the catalog in a single day without time traveling. I used to use this trick all the time when trading with others in the game. You could also force smaller orders (less than 5 items) to be sent by going to the post office and sending enough letters to finish filling up the back desk (catalog orders filled up a space here), which would cause all mail to be sent immediately. Each other game forces you to wait until mail is sent (6am and 5pm in WW-NL, and 6am only in NH).
NH's problem here is that mail is only sent once a day, meaning the catalog queue only gets cleared once a day. Having mail sent twice a day like in older games would double the amount of orders one could place. Having a system closer to GameCube would definitely benefit a game that has as much of a focus on decoration as NH does, but I feel that would be asking too much and definitely would not expect that particular feature to make a return. But only 5 a day is just too small in my opinion.
