I pre-wash and iron with sizing before cutting. Although I machine piece, I hand quilt. If I am going to spend 9 months to a year to finish a quilt, then I'm not taking any chances that the fabrics will run or shrink. Besides, I enjoy all the processes of making a quilt, including the ironing and cutting. I'm not one to just want to 'get it done' so I can go on to the next quilt.