I know what you mean about washing already cut pieces Nor'easter! I found out how tough that is after the fabric squares swap.
It was not so bad after I started washing them in a garment bag and ironed carefully, but I think the squares will all have to be recut to make them the same size.
I am making my own strip rolls for later. This means they are already washed and ironed!
If a person doesn't want the hassle of all those strip tangled together and having to iron or recut them, swap with Ruth using only preshrunk fabrics.