it is important to use the proper foot for your machine- for the chosen stitch -- if you try to do a decorative stitch with the wrong foot on you can easily break your needle- which can be dangerous- or mess other things up-
decorative stitches are great design features when used for quilting- be adventurous-
but if you plan to quilt a pieced top= your practice piece should also be pieced--not necessarily the same-but some seams- and the same fabrics-batt as the real thing--if you want to see how (your) real one is going to come out.