Enriched Stitch did a lovely stitch guide for Ewe and Eye's Swirly Snowmen (it shows an overhead view of three snowmen twirling in the snow to make their scarves fly out around them), and had a customer ask if the guide could be used for the smaller single snowman ornaments that Ewe and Eye produced. Yes! Quite a few designers do a large painted canvas and then reuse elements from the large design in a smaller version. If I've done a model for a larger or smaller piece and the guide can be reused in that canvas' other versions, I will note what you need to do in the stitch guide. When it comes to other stitch guide writers, any shop or the stitch guide writer him- or herself can tell you if you can reuse a guide on another canvas.
Of course I collect guides for their ideas and reuse them other places all the time, but this is really about using a guide for another version of the same design.