I either use a pin on the end I just finished sewing to, or use a piece of blue painter's tape, then I know to switch ends and either can easily be removed. I had not thought of sewing across the end, great idea though. Thanks.
I have also seen somewhere that when sewing the border on a quilt to do it the same way, sew one side or end in one direction, and turn it and sew the other side or end in the other direction. I have started doing this myself. Hope this helps. There are always so many neat ideas on this board.