Yeah, the 400-degree rule is a game changer. I read this whole article about how frozen fries need that initial high heat blast to vaporize the ice crystals fast, otherwise you're just steaming them. That's why 375 gives you that sad, soggy result. For fresh cuts, I've heard you gotta soak them in cold water first to pull out the starch, then pat them bone dry. Crank it to like 425, and they might need 20-25 minutes depending on how thick you cut them.
Wait, soak them overnight? That's crazy, I can't imagine planning fries a whole day ahead. I tried the cold water soak once for like an hour and got bored. Doing it overnight sounds like a huge pain for something that might still turn out soggy. I'm sticking with the high heat method, it just makes more sense.