I always get a better result after ironing the fabric, on almost anything, and it is a must sometimes. I even irion edges, seams, hems, bumps, binding, etc, and it makes a difference. I don't know if there is any way about it. It makes layers flatter and more even against each other. For the long strips, there is a trick to lift them up after the needle is lowered, slightly stretching the pieces and aligning the layers as you go along. This is when a walking foot can improve results too.