In a normal file, every point is a stitch. In a sequin file, some points are instructions to the sequin device: drop a sequin here, tack it down, move on. The spacing between drops has to match the sequin size, or they overlap and stand up, or leave gaps that show the fabric.
Direction matters too. Sequins lie best when they follow one clean path through a shape, the way scales lie on a fish. A path that doubles back or changes direction sharply leaves sequins tilted and catching the light unevenly.
And the machine has to switch cleanly between the sequin device and normal embroidery. We place those switches so the device is only engaged where sequins belong, and the rest of the design sews as ordinary stitches.
Before you order, check your machine. Sequins need a sequin device fitted to the machine: without one, the sequin commands in the file are ignored or stop the machine.