I have seen some embroidery designs that are made for quilting blocks. I can't wrap my head around how you would use these. Do you quilt the top before you make the sandwich? Before you sew the block into the quilt top? After the whole quilt is put together?

I have an older Janome 10000, I can't imagine it would be able to handle moving a whole quilt around to accuragely sew a quilt design on a block that is already incorporated into an entire quilt. Before I jump into this and purchase software designs, I want to get more information about how it is done. My Janome Dealer just said, "Oh yes, it works!" I want "been there, done that" testamonials before I decide to try this. Has anyone done this? What a foolish question, of course someone has done this--can you tell me how to do it?