starch will also help stabilize the bias edges before joining them- I generally remove the papers as soon as I have joined the blocks- long before completing the whole quilt top; but I leave the papers on until they are attached to the next blocks-just for the stability. if it makes sense at the time to remove the paper first I stitch a small 'stay-stitch' all the way around the block inside the seam allowance- then I starch & press well. lots of paper pieced blocks are used along with parts that are not paper pieced-