As stated somewhere above, LSS can be pieced together for custom sizes and shapes. Every piece is usable, no matter how small.
Larger scraps can be turned, cut and pieced into free-form shapes. LSS will hold with edge-to-edge gluing, stapling, cement, tarring, or sintering with lead. You won't be able to stitch through the latter three, but they are interesting to note.
Smaller scraps can be used to create elevated areas. Position scraps with a small dab of glue-stick; a few stitches will hold it in its final place. You can build up layers: closer outer edges will make a gentler rise (think "topography maps").
Teensy-Weensy scraps are the best! Those tiny snippets from trimming corners or shaping pieces can be collected in little zip-shut baggies. Combined with cotton-wool, you can make them into small rolls that create gentle curves and support odd-shaped cabs like large pointy-back crystals, natural stones, or found objects. The cotton-wood softens the lines of starker angles and the bits of LSS give you anchors for stitches as you create your shapes.
Cabochon crystals with pointed backs can be mounted with an in-filling ring of bits of LSS and cotton-wool. Mark the spot where you want the crystal to be by turning it upside and drawing around it with a soft pencil or fine-tip permanent marker on the LSS. Mark within where the contact point will be. Roll the little snippets gently together with a very small amount of pulled-start cotton ball, and run the glue stick lightly around the shape you drew. (The small amount of glue from a glue stock can be stitched through, unlike the silicone glue.) The snippet mix can be carefully colored with a permanent marker once it's in place, preferably before the crystal is glued in. (Slips of the marker can be cleaned off the crystal with an alcohol wipe). Put your snippet roll down on your line of glue stick, then a tiny dab of E-6000™-type glue anchors the point right side up on its mark. The glue stick holds the ring as you stitch it into place around the crystal, once the silicone glue has set.
Make sure the ring is even but not too tight, and fills in up to the top of the crystal. Once you put on your first rows of beads, you can follow this step with a secondary in-filling to make a sloping surface down or a ruffle up if the fancy takes you. Using larger snippets, instead of the stabilizing matrix of cotton wool, can also accommodate pointy backs of irregular shapes.
Beadscaping sections of a piece are done in similar fashion. Make a note to yourself where you want a swell or a curl, and prepare a mixed roll of scraps and cotton-wool. Color it with permanent marker to either contrast or blend in, and shape it on the LSS first. If it is a section larger than 40mm to 50mm in width, stitching in underpinnings of larger pieces of scrap LLS is a good idea. Beading special shapes is a judgement call—depending on your style of working, and the shapes and contours of your piece, you may want to do the special shapes first, or you may want to do all the background first. Flip a coin. (Multi-task: look for dropped beads while you are down on the floor looking for the coin).
Thanks and love to Lace, Jackie and Jack (and Steffie, too).