It depends if you are rastering or vector cutting. Some of the Chinese software call this 'scan' or 'cut'.
In 'scan' mode the machine is going back and forth like an inkjet printer, building up the design one pixel at a time. The scan gap, lpi or dpi setting will adjust the spacing from line to line. If the speed is set too high it can skip the index step so just keeps going over the same line. The X-axis can generally move faster than the Y-axis due to inertia (depends on how your machine is configured).
If you set the job to vector cut a square and use a minimal speed, does it cut correctly?