I always test the design myself in one format so I'm absolutely sure it stitches out OK in that format. Then I have a few other formats tested by others.
Once I had someone test a design for me which had a shadow over the normal stitching. She decided to use the mask-function in her software to delete the underlying stitches and complained the density of the shadow was too light - no wonder. That is not the typical response, thank goodness, most testers are terrific, but it made me aware of being clear to state what I want to know: the material and stabiliser used, outlines without gaps, any problems they had, etc.
I can do test stitching. Format is .jef
Would have sent PM but not sure how to do that.
I´m interesting to test for you, I´m doing Hus and Pes also Vip, Dst, Pcs I can say almost every formats exept Art.