For the most part I don't care much for needle turn or edge turned under applique. I do tons of fusible web applique. You can do a raw edge technique where you just sew with invisible thread right along the edge or you can do a variety of different edge finishing techniques, satin stitch, tiny zig zag, blanket stitch, or fancy stitching. With just the blanket stitch alone you can make it tiny and elegant or big and bold with a more folk arty look.
Applique is totally up to the individual. No one way is the right or wrong way.