Setting the stitch lenght to 1.5 is not a requirement, but a recommendation. The frequency the needle moves at is determined by the speed of the sewing as well as the stitch lenght. If you stitches are set too long the needle will stay up longer waiting until is time to move down again to achieve the desired stitch lenght. It is a very short time, but it may cause your stitches to look jerky. If you set up the stitches to be short, 1.5 or smaller, the needle will be ready to come down any time, and the speed of the stitches will only be determined by the speed you move the fabric at.
I do have one question. Because the sensor of the machine is a little red light on the fabric, I heard somewhere the the BSR does not work on red fabric. To me movement is movement, regardless of the color of the fabric. Have anyone tried this? I went to try and found no red fabric in my stash to go play with. I guess is time to go get some.
Maria