You can dry frozen ones after they thaw?I never have. I treat the parchment like the drying sheets, but use them when making things that stain, like tomato leather. Also, depending on what you're doing...say something fairly gloppy, you can tape up the sides into a mini flat "cookie sheet". Wax paper too.
That is if your dryer has the space to do so and the fan oomph to handle the extra work it creates. I use this method a lot when I want to dry thin tomato sauce (no thickener added) into tomato brittle that I then toss in the food processor for tomato powder/bits. Excellent for flavoring soft cheeses, sprinkling on top of casseroles, or making soups/broth like you would with bullion.