NeeDoh in fridge overnight or longer?

As we all know, we're not supposed to freeze the NeeDohs. Since they got too soft (😭) I have been putting in the fridge until they're nice and hard. I was wondering if it's ok to keep one in the fridge overnight or even indefinitely. I have 2 I am swapping in nd out of the fridge but I am wondering if I get a 3rd would it be ok to sort if always have one in to swap out and also if I can keep one of mine in the fridge overnight so I have it hard in the morning.

Thanks!