To pre-shrink or not to pre-shrink.

[Warpy]

7. 3% shrinkage across the entire width of the quilt will add up to quite a bit

but 3% shrinkage between the lines of stitching will be unnoticeable or minimal, just causing the areas between the stitched lines to puff up very, very slightly.

I honestly don't think I'd preshrink it. Some commercially made quilts with cotton batting do shrink after the first wash but the effect makes them look less commercial and more handmade, so it's all good. The stitched lines, instead of sitting on the surface, are below the surface.

I think the only time I'd prewash is in an appliquéed quilt where you don't have the patterns of stitching and don't want what you do have to appear more pronounced.