I realize it was like this in New Leaf as well, but I don't understand why Joan feels the need to disappear at noon. She's the only NPC that disappears at such an early hour, and it's extremely inconvenient if you have any kind of Sunday obligations. Why could she not disappear at 6 PM at the earliest? Why does she have to disappear during the day at all? You can't sell turnips on Sunday anyway, so it's not like you risk breaking the game by having her stay just a little longer. I just want to buy turnips!!!