I cut the strings as I go along. I know that not everyone does. I sent a quilt off to an LAQ on the board and paid more than I normally do and there were many loose threads on the quilt when I got it back. I was fine with the quilting but not the loose threads. I think it is easier to do as you go along rather than all at once. Mine was a King Size quilt and it took quite a while to cut all the threads. I guess it is up to the one doing the work.