I haven't done this in a bazillion years, and when I last did it, I was following a traced line, not trying to sew so the zigzag falls just a hair outside the edge of an applique. Thus, if you get within about a foot of the piece, you can see irregularity in some parts of the stitch lines. Considering that it looks fine from a normal viewing distance (even with bright light on the shiny embroidery thread) and that it's going on the back sash anyway, I really don't care. The one thing that annoys me is that I did get some puckering in the satin, but attacking the piece with a damp press cloth and iron set on synthetic seemed to help a lot. (I didn't just use the iron's steam feature because my iron only produces steam on higher temperatures that I'm scared to use on polyester.) The annoying pucker in the middle is basically gone. The ones near the edges aren't, but they'll be mostly hidden by gold trim anyway.
I'm guesstimating it will take me about 4-5 more hours of sewing to get this one done, and I have to break it up into chunks so my eyes and shoulder don't complain. (I'm using the hand wheel mostly - I don't have one of those machines that can be set to crawl along regardless of how much you push on the presser foot.) At least this entire process isn't taking quite as long as I thought it was going to.