I also quilt for a charity. I agree that you just do the best you can with what you are given. All the tops are made with the best intentions! I usually press the top before I quilt (even if it looks like it doesn't need it) this way I can predict issues before I get it on the frame. Sometimes it is quicker to take a border off & put it back on. If there is an extra thick intersection, you can hit it with some steam, then hit it with a hammer. You can also use a tailor's clapper.